New Publications are available for Photoconduction and photovoltaic effects; photodielectric effects
http://dl-live.theiet.org
New Publications are available now online for this publication.
Please follow the links to view the publication.Solar Photovoltaic Energy
http://dl-live.theiet.org/content/books/rn/pbrn009e
<p xmlns="http://pub2web.metastore.ingenta.com/ns/">This professional manual on photovoltaic energy gives designers, installers and managers the tools and methods for: the effective writing of technical reports; and calculating, installing and maintaining the necessary components (solar panels, batteries, charge controllers, conductors, etc.) with the aim of designing and putting in place photovoltaic installations adapted to specific needs, conserving energy and taking into account both the opportunities and limits of this new energy. It gives a detailed account of the physical phenomena (conversion and storage of solar energy) as well as the available technology and the technology currently in development. This edition includes a number of updates on the economical and technical aspects of this energy, as well as exploring the possibilities of connecting it to a network of photovoltaic systems. This book is an essential tool for technicians and engineers involved in the field of solar energy (installers and users), as well as professional researchers. It will also be a useful reference for engineering students,
including those in electronic engineering.</p>Polymer electronics - towards the future
http://dl-live.theiet.org/content/conferences/10.1049/ic.2009.0061
This presentation discusses some key characteristics of polymers and several polymer-based electronic devices such as polymer light-emitting diodes, photovoltaic diodes, organic solar cells, field-effect transistor, and electrophoretic display. (31 pages)Characterization of nanometer scale titanium film oxidation lines and MIM tunneling junction structures
http://dl-live.theiet.org/content/conferences/10.1049/cp_20060806
In the novel photoconductive semiconductor switch (PCSS) used in ultra-high speed electric-opto sampling system (EOS), the nanometre scale metal-oxide-metal (MIM) junction is the basic structure of the PCSS. The substrate is LT-GaAs or oxygen ion implanted SOS material. Above it, there is a 3~5 nm thick sputtered Ti film that are fabricated into MIM structure by the atomic force microscope (AFM) using anodic induced oxidation method combined with photolithography method. The chemical/physical characteristics of nano Ti film and nano oxidation line determine the operating property and reliability of such nano devices. In this paper, the characteristics of nano Ti film, nano oxidation lines and MIM junctions are measured by AFM, X-ray photoelectron spectroscopy (XPS) and semiconductor analyzer. The nanooxidation lines are fabricated under air ambient, room temperature, the relative humidity is about 30%, oxygen density is about 20% and with tip scan speed is about 0.1 μm/s during the fabrication process. The results indicate that with various bias voltages between AFM tip and Ti film during fabrication, different line width and different MIM's I-V characteristic can be obtained, and the methods mentioned above optimized the fabrication conditions further.Observation of charge behavior in organic photoconductor using the pulsed electroacoustic method and pressure wave propagation method
http://dl-live.theiet.org/content/conferences/10.1049/cp_19961003
Recently, many methods to measure the space charge distribution in solid dielectrics have been developed, such as the laser-induced pressure wave propagation (LIPP) method by means of the pulse laser, the pressure wave propagation (PWP) method by means of the piezo-electric transducer, and the pulsed electroacoustic (PEA) method. In this report, the resolution of PWP method using a piezo-electric transducer as a generator of acoustic pulse wave has been improved. To improve the resolution, a new technique to generate the narrow acoustic wave was employed. In consequence of the usage of this new technique, we have succeed to obtain the resolution of about 10 μm. The principle and the result of this technique will be introduced here. Furthermore, a typical measurement result of carrier generation, drift and trapping in an organic photoconductor (OPC) will be introduced and compared with the result obtained using PEA method.Inspection of materials for advanced sensors
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951516
The main objective of this paper is to describe a research project on the integration of advanced versions of several known experimental techniques into an economic and versatile intelligent system for investigation of surface and bulk properties of a wide range of high resistivity materials and devices. The properties include metal/insulator contact, surface, bulk and interface trapping, surface and bulk resistivity, space charge effects and dipole processes, photoinduced and dark decay of surface charges and charge carrier transport. Effect of temperature, gases and pressure on these properties can also be investigated for developing new sensors. (6 pages)The gas sensing properties of chloro-aluminium phthalocyanine thin films
http://dl-live.theiet.org/content/conferences/10.1049/ic_19951513
The behaviour of ClAlPc thin film gas sensors is studied in the presence of NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> and O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>. The change in the dark conductivity of ClAlPc thin films on exposure to NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> at several different temperatures is investigated. In particular, the temperature of maximum sensitivity (T<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">max</sub>) and the minimum temperature for good reversibility (T<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">min</sub>) of ClAlPc thin films has been determined and related to gas sensor applications. Sensitivity (s) of ClAlPc to NO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> is also measured at several different temperatures. It is found that by increasing temperature the sensitivity decreases, but reversibility is greatly enhanced. (18 pages)Controllable synthesis of rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanorod array, nanoflowers and microspheres directly on fluorine-doped tin oxide for dye-sensitised solar cells
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0398
TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> films with different morphology directly grown on fluorine-doped tin oxide (FTO) substrate were prepared via a facile hydrothermal method. Rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanorod arrays, nanoflowers film and microspheres film were obtained by changing the volume ratios of HCl and CH<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">3</sub>COOH in solvent with other conditions unchanged, as confirmed by X-ray diffraction, scanning electron microscopy, transmission electron microscope (TEM) and high-resolution TEM. Dye-sensitised solar cell (DSSC) assembled with the TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> microsphere films grown on FTO substrate as photoanode achieves an overall photoelectric conversion efficiency of 1.94% and a short-circuit current intensity of 5.12 mA cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−2</sup> owing to the rough surface, which is higher than those of nanorod array and nanoflower-based DSSCs. The photovoltaic performance of rutile TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> film-based DSSCs is related to the morphology of the film.New materials and processes for flat panel X-ray detectors
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_20030555
Flat panel X-ray imagers using amorphous silicon active matrix addressing have been introduced to the medical imaging market at sizes up to 40×40 cm and with up to 10 million pixels. Some new technology developments, which can further increase the performance of these devices, are described. High atomic number polycrystalline X-ray photoconductors can operate near the theoretical sensitivity and at reasonably low bias voltages. The higher sensitivity obtained in HgI<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> allows single-photon detection, which opens up new imaging opportunities. Another approach to improve sensitivity is to integrate an amplifier at the pixel level, which requires laser-recrystallised polysilicon transistors. A pixel-level source follower amplifier is shown to have enough gain to overcome other noise sources. A three-dimensional device structure is needed to accommodate the pixel electronics, and so the sensor is deposited on top of the electronics, separated by a thick passivation layer. Future possible detector technologies based on printing and organic semiconductors are discussed.Photoconduction in Langmuir–Blodgett films of octasubstituted metal-free phthalocyanine molecules
http://dl-live.theiet.org/content/journals/10.1049/ip-cds_19990268
In-plane steady-state photoconduction in Langmuir–Blodgett (LB) films of octasubstituted metal-free phthalocyanine molecules have been studied over a temperature range between 78 and 293 K. Deep-level traps localised at grain boundaries of multicrystalline films are believed to be responsible for both dark conduction and photoconduction. Slow and fast relaxation mechanisms are identified from measurements of transient currents. Small changes of substituting chains in the molecule are found to have significant influences on rate and quantum yield of photogeneration of charge carriers in LB films.Photovoltaic effect in threads covered with CdS
http://dl-live.theiet.org/content/journals/10.1049/el_20010683
A report is presented on the photovoltaic effect in CdS/Cu<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2-<i>x</i></sub>S films deposited on trylene threads at temperatures close to room temperature from using the water solutions of complex-salt compounds. Results demonstrate the feasibility of using this material for photovoltaic applications for electro textiles and wearable electronics applications.High quantum efficiency metal-semiconductor-metal ultraviolet photodetectors fabricated on single-crystal GaN epitaxial layers
http://dl-live.theiet.org/content/journals/10.1049/el_19971322
The authors report a GaN metal-semiconductor-metal photodetector with high quantum efficiency (~50%) in the absence of internal gain. These photodetectors have a flat responsivity above the bandgap (measured at ~0.15 A/W) with a sharp, solar-blind cutoff at the band edge. There is no discernible responsivity for photons below the bandgap energy. In addition, a very low dark current was obtained, measured at ~800 fA at –10 V reverse bias.Photoconduction in bacteriorhodopsin/GaAs heterostructures
http://dl-live.theiet.org/content/journals/10.1049/el_20010426
Observation of transient and steady-state photoconduction across an indium tin oxide (ITO)/bacteriorhodopsin(bR)/GaAs heterostructure, with the bacteriorhodopsin acting as the light-sensitive material, is reported. The protein is dissolved in polyvinyl alcohol and the film dried after deposition. The steady state photoconduction is probably caused by the pH change at the bR/ITO interface owing to proton release from the bR upon photoexcitation, and is therefore an electrochemical effect.Scanning force microscope cantilever for voltage sampling with ultrafast time resolution
http://dl-live.theiet.org/content/journals/10.1049/el_19990720
A scanning force microscopy (SFM) cantilever for the investigation of ultrafast signals is presented. High temporal resolution is achieved by integrating a photoconductive switch within a coplanar waveguide structure onto a low temperature GaAs/GaAs cantilever. Experimental results and numerical calculations of the detection of picosecond guided electrical signals based on the optoelectronic technique of photoconductive sampling are presented.Favourable photovoltaic effects in InGaN <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cell
http://dl-live.theiet.org/content/journals/10.1049/el.2009.2094
InGaN <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cells with different In content (x=0.02/0.12/0.15) have been fabricated. The measured open-circuit voltages (<i xmlns="http://pub2web.metastore.ingenta.com/ns/">V</i><sub xmlns="http://pub2web.metastore.ingenta.com/ns/">oc</sub>) are 2.24, 1.34 and 0.96 V, respectively. All the devices exhibit large fill factors of more than 64% and enhanced response in the short wavelength region, suggesting the high potential of InGaN-based <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> homojunction solar cells.Electrical properties of 1.55 µm sensitive ion-irradiated InGaAs with subpicosecond carrier lifetime
http://dl-live.theiet.org/content/journals/10.1049/el_20030441
Carrier lifetimes as short as 270 fs with carrier mobility of 200 cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>/V/s and good performances in terms of layer resistivity have been obtained from ion-irradiated InGaAs. The residual carrier concentration measured in Hall effect experiments was found to be weakly modified in spite of the high defect concentration created by the ion bombardment. Ion-irradiated InGaAs appears to be specially adapted to fast photoconductive devices operating at optical communication wavelengths.Strong normal-incidence infrared absorption and photo-current spectra from highly uniform (In,Ga)As/GaAs quantum dot structures
http://dl-live.theiet.org/content/journals/10.1049/el_19980589
The authors report normal-incidence infrared absorption in the wavelength range 12 – 14 µm and low temperature (40 K) photo-current spectra from an (In,Ga)As/GaAs quantum dot structure. The basic structure consists of 20 periods of highly uniform (In,Ga)As/GaAs dot arrays. The strong room temperature absorption indicates the high quality of the superlattice structure; this is considered to be very promising for the fabrication of high performance, long wavelength photodetectors.<i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-diamond/<i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-GaAs junctions formed by direct bonding
http://dl-live.theiet.org/content/journals/10.1049/el_19960018
The direct bonding of an <i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-GaAs thin film onto the surface of epitaxial <i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-diamond is demonstrated. A rectifying characteristic is obtained for the present <i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-diamond/<i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-GaAs bonded junction system. Moreover, the occurrence of the photovoltaic effect at the junction is observed under illumination by an AlGaAs laser operated at 789 nm. A diamond/GaAs <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pn</i> junction can be formed by direct bonding.Suppression of space charge effect in MIC-PD using composite field structure
http://dl-live.theiet.org/content/journals/10.1049/el.2010.0964
A maximised induced current photodiode with a novel composite field structure that suppresses the space charge effect achieved a 2 V bias operation for an average photocurrent of 4 mA with a 3 dB bandwidth of over 35 GHz.Quantum confined Stark effects of heavy-hole confined states in In<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.53</sub>Ga<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.47</sub>As/In<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.52</sub>Al<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.48</sub>As multiquantum well structure using photocurrent spectroscopy
http://dl-live.theiet.org/content/journals/10.1049/el_19981189
Photocurrents in an In<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.53</sub>Ga<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.47</sub>As/In<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.52</sub>Al<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.48</sub>As multiquantum well structure containing 10 nm wide wells were measured at room temperature. The spectra showed fine steplike structures accented by exciton peaks of interband transitions. The exciton peaks of heavy-hole transitions responded very sensitively to the electric field due to the quantum confined Stark effect. The energies of the experimental confined states of the heavy-hole extrapolated from the larger electric field were roughly proportional to the squares of quantum numbers. The nonparabolicity of an effective mass of the heavy-hole was surmised to be very small in a direction normal to the well plane.Photovoltaic effect in CdS on flexible substrate
http://dl-live.theiet.org/content/journals/10.1049/el_20010328
The authors report on the photovoltaic effect in CdS/CuS films deposited on flexible substrates at temperatures close to room temperature from using the water solutions of complex-salt compounds. The results demonstrate the feasibility of using this material for photovoltaic applications requiring covering of large complex surfaces.Dimensional control of titanium dioxide nanotube arrays with hydrogen peroxide content for high photoelectrochemical water splitting performance
http://dl-live.theiet.org/content/journals/10.1049/mnl.2012.0237
Adding hydrogen peroxide (H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>) for the fast formation of titanium dioxide (TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>) nanotube arrays produce smooth and clean TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanotubes without bundling and cracking problems. The nanotube formation rate accelerated after the periodical addition of H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> at different intervals. Adding H<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>O<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> at 10 min intervals formed longer nanotubes (13 µm) with larger pore diameters (140 nm). These novel TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanotubes exhibited optimal photocurrent density (1.8 mA/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>) and 3.8% photoconversion efficiency because of high crystallinity with numerous oxygen vacancies in the large pore diameters allowed for better light absorption and good interaction between the electrolytes and TiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub> nanotubes.Self-biased saturable absorber mirror demonstrating very low saturation fluence
http://dl-live.theiet.org/content/journals/10.1049/el.2010.1981
The performance of a self-biased saturable absorber mirror operating via the Franz-Keldysh effect is studied experimentally. Very low saturation fluences, less than 1 µJ/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup>, are obtained. Results agree well with theoretical predictions.Influence of UV illumination condition on NDR performance of porous silicon superlattice
http://dl-live.theiet.org/content/journals/10.1049/el_19961069
The authors report on the influence of the UV illumination condition on the negative differential resistance (NDR) performance of a porous silicon superlattice. It is found that the peak-to-valley current ratio (PVCR) can be improved by increasing the off-time of the illumination in each period.Ultra-high frequency monolithically integrated quantum well infrared photodetector up to 75 GHz
http://dl-live.theiet.org/content/journals/10.1049/el_20057428
An integrated quantum well infrared photodetector for ultra-high speed and frequency sensing in the mid-infrared has been developed. The photodetector is mounted on a microwave connector with either a ‘K’ or ‘V’ connector. The device was characterised at a temperature of 100 K by optical heterodyne generation of photocurrent in the frequency range DC to 75 GHz. Photoresponse at 75 GHz was approximately 30% that at DC, indicating very fast performance.To suppress dark current of high temperature β-SiC/Si optoelectronic devices with porous silicon substrate
http://dl-live.theiet.org/content/journals/10.1049/el_20001291
The suppression of high temperature dark current in a β-SiC/Si optoelectronic device with a porous substrate has been studied. A <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pin</i> structure was used to demonstrate the applicability. Experimental results show a 12-fold improvement in optical gain at 200°C operating temperature for the sample prepared on a porous silicon substrate compared to the sample prepared on a Si substrate. The improvement is attributed to the suppression of dark current by the high resistivity and flexibility of the porous substrate.High-performance back-illuminated solar-blind AlGaN metal-semiconductor-metal photodetectors
http://dl-live.theiet.org/content/journals/10.1049/el_20001301
The fabrication and characterisation of back-illuminated solar blind AlGaN metal-semiconductor-metal photodetectors is reported. The dark current of 40 × 40 µm devices is lower than the instrument measurement limitation of 20 fA for a bias < 100 V. The external quantum efficiency is as high as 48% and the spectral response shows a sharp band edge drop-off at ~280 nm.Dark current optimisation for MOVPE grown 2.5 µm wavelength InGaAs photodetectors
http://dl-live.theiet.org/content/journals/10.1049/el_19980560
The authors have obtained state-of-the-art dark current densities of typical 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">–9</sup> A/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> (150 K, –10 mV) for 2% mismatched In<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.82</sub>Ga<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">0.18</sub>As photodetectors, by optimising the <i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-type doping level of the absorbing layer. It is demonstrated that the dark current can be decomposed into three different contributions. The decreased optical response accompanying higher doping levels, remains acceptable.Electronic properties of filtered cathodic vacuum arc (FCVA) deposited silicon thin films
http://dl-live.theiet.org/content/journals/10.1049/el_19961325
The electronic properties of silicon films deposited in a filtered cathodic vacuum arc (FCVA) from a highly doped silicon target have been studied by the authors, and correlated with growth conditions. Films with the best electrical properties were deposited with elevated growth surface temperatures (200–300°C) and low background pressures (~10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-4</sup> torr) of hydrogen. The number of times that the cathodic arc had to be retriggered during the deposition of a film also significantly affected its electronic properties. Room temperature photo-conductivities ~10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-6</sup>(Ω.cm)<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">-1</sup> have been measured at AM1 illumination. This is the first time photo-conductivity has been observed in FCVA deposited silicon.High-responsivity porous-SiC thin-film <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pn</i> junction photodetector
http://dl-live.theiet.org/content/journals/10.1049/el_19981547
A porous-SiC thin-film photodetector with a <i xmlns="http://pub2web.metastore.ingenta.com/ns/">pn</i> junction structure has been successfully fabricated on an Si substrate. The developed device exhibits a high responsivity of 0.4 A/W at 25°C for 650 nm irradiation. In particular, the device has a responsivity of 0.35 A/W and a photo/dark current ratio larger than 100 at 200°C, indicating its potential capability for high-temperature operation.Visual indication of locally varying photoconductivity
http://dl-live.theiet.org/content/journals/10.1049/ip-i-1.1984.0022
The paper deals with the visual indication of a locally varying carrier density or photoconductivity, which is optically generated within a semiconductor substrate and extends over a distance of some millimetres up to some tens of millimetres. The induced profile is conventionally displayed on a CRT using a special substrate-edge excited microstrip device that works as the sensing element. The technique can be adapted to CW or pulse excitation, and allows an immediate study of absorption and diffusion effects under varying excitation conditions.Emis data reviews. Properties of amorphous silicon: a book of EMIS data reviews
http://dl-live.theiet.org/content/journals/10.1049/ip-i-1.1985.0049
Theoretical analysis of the Hall effect photovoltaic cell
http://dl-live.theiet.org/content/journals/10.1049/ij-ssed.1979.0016
A theoretical analysis is given describing the Hall effect photovoltaic cell. By illuminating a homogeneous semiconductor, a diffusion of holes and electrons will occur in the direction of decreasing light intensity. Due to the Hall effect, caused by an external magnetic field, holes and electrons will be declined in opposite directions so that a net current will flow through the end contacts. Despite simple arguments indicating that choice of geometry and conductivity could give both high open circuit voltage and efficiency, the detailed analysis indicates that the photoconductivity of the material reduces the internal resistance and leads to low efficiencies.The electric and photoresponse characteristics of Ge/ZnSe heterojunctions
http://dl-live.theiet.org/content/journals/10.1049/ree.1971.0082
Wide band gap II-VI compounds deposited epitaxially upon semiconducting substrates have possible applications as solid-state infra-red detectors and imaging devices. The Ge/ZnSe heterojunction has been prepared by vacuum evaporation of epitaxial layers of zinc selenide on to orientated, single crystal, p-type, germanium substrates. Measurements have been made of the electrical characteristics, capacitance properties and photoresponse of these junctions. From these measurements a realistic band model has emerged involving intrinsic and extrinsic defects present in the bulk and interfacial region of the zinc selenide. The data presented suggest that a Mott-type barrier rather than a Schottky barrier is present at the germanium-zinc selenide interface. Techniques are described for reducing the magnitude of this Mott barrier and the resulting change in the physical properties and band structure are discussed.Back side reflection influence on quantum efficiency of photovoltaic devices
http://dl-live.theiet.org/content/journals/10.1049/el_19880746
A method is proposed for calculation of the quantum efficiency of photovoltaic devices, which takes into account the back side reflection and corresponding surface recombination rates. The applied technique enables simple theoretical prediction of basic photovoltaic device parameters.Chaotic behaviour in an illuminated semiconductor–(thin insulator)–semiconductor structure
http://dl-live.theiet.org/content/journals/10.1049/el_19900894
A new chaotic behaviour circuit with an illuminated ITO–SiO<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sub>–(<i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>–<i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i><sup xmlns="http://pub2web.metastore.ingenta.com/ns/">+</sup>)Si structure has been proposed. It has been shown that the spectrum of chaotic self-oscillations can be controlled by illumination.Picosecond lifetime measurement in semiconductor by optoelectronic autocorrelation
http://dl-live.theiet.org/content/journals/10.1049/el_19910637
A novel optoelectronic autocorrelation technique for measuring picosecond lifetimes in semiconductors is described. The technique is based on the nonlinearity of the photovoltage dependence on the optical excitation level. Numerical simulation as well as experimental results for low-temperature epitaxial InGaAs samples are presented.Non-steady-state photovoltage in crystals with long photoconductivity relaxation times
http://dl-live.theiet.org/content/journals/10.1049/el_19900821
The effect of non-steady-state photovoltage in photoconductive crystals for high excitation frequencies is discussed. The theoretical analysis based on the widely accepted model of a photoconductor with one partially compensated donor level and a finite photoelectron lifetime is in reasonable agreement with the expirements on cubic BSO crystals. Average lifetimes of photocarners in the samples were estimated to be τ = 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−4</sup> s for λ = 442nm and τ = 3 × 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−6</sup>s for λ = 663 nm.Lateral drift and recombination of photogenerated carriers in multiple quantum well hetero <i xmlns="http://pub2web.metastore.ingenta.com/ns/">nipi</i> structures
http://dl-live.theiet.org/content/journals/10.1049/el_19901252
The lateral spreading of photocarriers in a multiple quantum well hetero <i xmlns="http://pub2web.metastore.ingenta.com/ns/">nipi</i> structure is reported. The physical behaviour of the carriers is explained by a simple model. The results indicate the importance of decreasing the lateral device dimensions in order to obtain a large absorption change and a corresponding large change in the refractive index at low power levels.Detection of acoustoelectric voltage by shear-horizontal-plate waves in cadmium-sulphide plates
http://dl-live.theiet.org/content/journals/10.1049/el_19730115
A novel configuration employing shear-horizontal-plate waves is used to detect acoustoelectric voltage in photoconductive cadmium sulphide. A theoretical expression (neglecting diffusion effects) for the voltage is also given.Quantum confined Stark effect in GaInAs/InP single quantum wells grown by low pressure MOVPE
http://dl-live.theiet.org/content/journals/10.1049/el_19880884
We report the first measurements of the quantum confined Stark effect in single GaInAs/InP quantum wells using photocurrent spectra from a single 80 Å well. Well resolved excitonic features are observed for values of electric field up to 3 × 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">5</sup> V/cm, whose field dependent shift and peak height are in excellent agreement with the predictions of an effective mass calculation, thus demonstrating that there are no intrinsic factors limiting this effect in the GaInAs/InP material system.Erratum: Effect of illumination and gate bias on flat-band voltage in plasma CVD Si-N on <i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-Si MIS structure
http://dl-live.theiet.org/content/journals/10.1049/el_19810600
Shallow donor impurities in InP bulk crystals grown by the synthesis, solute-diffusion technique
http://dl-live.theiet.org/content/journals/10.1049/el_19860014
Far-infra-red photoconductivity measurements are used to study residual shallow donor species in InP bulk crystals grown by the synthesis, solute-diffusion technique. The observation of 1s-2p, <i xmlns="http://pub2web.metastore.ingenta.com/ns/">m</i> =+ 1 Zeeman transitions between the shallow donor-impurity states reveals that two dominant residual donors are included in the InP bulk crystals having carrier concentrations of less than 1 × 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">15</sup> cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−3</sup> The donors are tentatively identified as Si and S.Examination of grain boundaries in polycrystalline solar cells using a scanning optical microscope
http://dl-live.theiet.org/content/journals/10.1049/el_19780340
A scanning optical microscope in which the object is scanned mechanically is used to produce images from polycrystalline solar cells using both the reflected-light and photoinduced current modes.Extrinsic photoconductivity in platinum-doped silicon
http://dl-live.theiet.org/content/journals/10.1049/el_19800640
Both <i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>- and <i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-type silicon have been doped with platinum and characterised by measurement of carrier concentration profile, resistivity/temperature, Hall mobility and conductivity measurements. It is concluded that photoconductivity is limited by recombination at uncompensated platinum centres in heavily doped material, and at 100 K by trapping at shallow levels.Photorefractive determination of the sign of photocarriers in InP and GaAs
http://dl-live.theiet.org/content/journals/10.1049/el_19850156
The sign of the majority photocarriers in semi-insulating iron-doped InP and undoped GaAs containing EL2 centres illuminated at 1.06 μm is unambiguously determined from the direction of beam coupling in a two-wave photorefractive mixing experiment previously applied to ferroelectric crystals. Majority photocarriers in these InP:Fe and GaAs:EL2 crystals are found to be electrons.Stability of aluminium-polysilicon photovoltaic junctions
http://dl-live.theiet.org/content/journals/10.1049/el_19810268
Aluminium <i xmlns="http://pub2web.metastore.ingenta.com/ns/">p</i>-type polysilicon contacts display a rectifying behaviour which exhibits an aging towards reduced Schottky barrier heights and increased <i xmlns="http://pub2web.metastore.ingenta.com/ns/">n</i>-values or ideality factors. The time scale for this aging process increases dramatically with the thickness of the aluminium layer in the range 100–1000 Å, and the overall behaviour is in accordance with the model of Ponpon and Siffert for transport of oxygen through the aluminium film to the polysilicon surface.Large-area low-frequency discharge-produced a-Si:H
http://dl-live.theiet.org/content/journals/10.1049/el_19820145
Using a capacitive glow discharge process at 380 kHz, very-large-area uniform films of a a-Si:H (60 cm diameter) have been deposited. The thickness uniformity, activated conductivity, photoconductivity and photoinduced effects in these films are discussed.Quantum confined Stark shifts in MOVPE-grown GaAs-AlGaAs multiple quantum wells
http://dl-live.theiet.org/content/journals/10.1049/el_19870733
We report the first observation of clear quantum confined Stark shifts in GaAs-AIGaAs quantum-well devices grown using metal-organic vapour-phase epitaxy.Shallow trap spectroscopy in InP:Fe
http://dl-live.theiet.org/content/journals/10.1049/el_19800225
Shallow traps in the range 10–500 meV are investigated on InP:Fe semi-insulating material. It is shown that some 12 major contributions can be selected; all are related to a monomolecular recombination kinetic implying that recombination takes place through numerous centres. Comparison is made for the deeper traps with d.l.t.s. results.Planar photodiodes made from vapour-phase epitaxial In<i xmlns="http://pub2web.metastore.ingenta.com/ns/"><sub>x</sub></i>Ga<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">1−<i>x</i></sub>As
http://dl-live.theiet.org/content/journals/10.1049/el_19790169
Planar photodiodes for the 1.0–1.3 μm wavelength range have been fabricated by diffusing Zn into vapour-phase epitaxial In<i xmlns="http://pub2web.metastore.ingenta.com/ns/"><sub>x</sub></i>Ga<sub xmlns="http://pub2web.metastore.ingenta.com/ns/">1−x</sub>As grown on a GaAs substrate. For compositions <i xmlns="http://pub2web.metastore.ingenta.com/ns/">x</i>=0−0.31, the dark current and spectral response are reported. The dark-current density for <i xmlns="http://pub2web.metastore.ingenta.com/ns/">x</i>=0.17 was as low as 5.4 × 10<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">−6</sup> A/cm<sup xmlns="http://pub2web.metastore.ingenta.com/ns/">2</sup> at <i xmlns="http://pub2web.metastore.ingenta.com/ns/">V<sub>B</sub></i>/2.