IEE Journal on Solid-State and Electron Devices
Volume 2, Issue 5, September 1978
Volume 2, Issue 5
September 1978
Devices and materials for 4 μm-band fibre-optical communication
- Author(s): C.H.L. Goodman
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 129 –137
- DOI: 10.1049/ij-ssed.1978.0046
- Type: Article
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The possibilities of optical communication at 4 μm wavelength are discussed. New materials are proposed for optical fibres capable of very low loss at this wavelength. The possibility of fabricating not only glass but single-crystal optical fibres at acceptable growth rates is suggested. A novel heterojunction system is described for making the necessary detectors and high-radiance sources, with the possibility of room-temperature operation. Advantages of optical communication at 4 μm rather than at 1 μm include relaxed demands on the precision of optical alignment (particularly important for single-mode operation), greater tolerance of transition metal impurities in the fibre as well as reduced scattering loss, and, therefore, the promise of much lower fibre loss if the required purity can be achieved. Extremely long stage lengths, e.g. 1000 km, should be possible if, as seems likely, fibre losses approaching 10−3 dB/dm can be achieved. Other possible wavelengths for optical communications are also discussed.
Some aspects of inverse bipolar transistor improvement through recombination reduction
- Author(s): Joseph C. Plunkett ; Jack L. Stone ; Adin E. Hyslop
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 138 –148
- DOI: 10.1049/ij-ssed.1978.0047
- Type: Article
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This paper describes the effect of recombination in the external base and epitaxial regions on the inverse current gain and related parameters of the n+pnn+ bipolar transistor. It is shown that the inverse current gain increases with the decrease in recombination in the external base region by use of the doublebase process. Improvement of the inverse gain is also shown with a decrease in epitaxial-layer thickness until it reaches a point of diminishing return at about one micrometre width between the space-charge regions. Breakdown phenomena related to the external base depth and the epitaxial layer thickness are also discussed.
Digital optical metal insulator silicon thyristor (o.m.i.s.t.)
- Author(s): A.G. Nassibian ; R.B. Calligaro ; J.G. Simmons
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 149 –154
- DOI: 10.1049/ij-ssed.1978.0048
- Type: Article
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149
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This paper presents a silicon device (m.i.s.t.), with an optical threshold, which can operate as a digital optical switch. Its operation and characteristics are presented. A good correlation between theory and the experimental results is obtained. The responsivity and sensitivity of 0.9 AW−1 and 3.9 × 10−4 mA/μV are obtained, respectively. Possible applications in fast optical digital isolation and in optical communication systems are envisaged.
Computation and measurement of the fluorescent infrared radiation from glow discharges in CO2-N2-He gas mixtures
- Author(s): J.W. Limbeek and J. Lucas
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 155 –160
- DOI: 10.1049/ij-ssed.1978.0049
- Type: Article
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The emission of 4.3 μm infrared fluorescent radiation from aglow discharge has been measured in six gas mixtures of varying proportions of carbon dioxide, nitrogen and helium. The results have been given as a radiation efficiency (ratio of radiation energy to the input electrical energy) and have been measured as a function of E/N (ratio of electric field to gas number density). A comparison has been made between the experimental results and the theoretical values for the range 3 × 10−21 < E/N < 56 × 10−21 Vm2. A good agreement has been obtained which verifies the calculated rates of vibrational excitation and confirms that relaxation processes are dominant for the E/N range investigated.
Time-of-flight measurements of electron transport parameters in CO2-H2-He gas mixtures
- Author(s): J.W. Limbeek and J. Lucas
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 161 –163
- DOI: 10.1049/ij-ssed.1978.0050
- Type: Article
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The drift velocity and longitudinal diffusion coefficient have been obtained for electrons in six CO2-N2-He gas mixtures with gas ratios 2:1:3, 1:1:8,1:2:3, 1:7:30, 4:1:12 and 1:1:3. A time-of-flight technique was employed to obtain accurate measurements in the range of 0.71 < E/N < 565 Td (E/N is, the ratio of electric field to gas number density and 1 Td = 10−21 Vm2). A comparison is made with the theorectical calculations of Lowke et al, the experimental values show good agreement at low E/N, but at high E/N the experimental values are larger than the theoretical values.
Infrared high spatial-resolution determination of doping levels in p-n junctions
- Author(s): J.C. White and J.G. Smith
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 164 –166
- DOI: 10.1049/ij-ssed.1978.0051
- Type: Article
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A nondestructive infrared emission-measurement technique, which allows point-by-point determination of the effective doping level within the depletion layer of a reverse-biased p-n junction, is described. The method is an alternative to normal capacitance-voltage techniques which give a value averaged over the entire junction area. With this technique a spatial resolution of about 15 μm is obtainable and a further advantage is that it is unaffected by high reverse currents.
Effects of fixed charges in the oxide of thermally oxidised m.i.s. solar cells
- Author(s): O.M. Nielsen
- Source: IEE Journal on Solid-State and Electron Devices, Volume 2, Issue 5, p. 167 –168
- DOI: 10.1049/ij-ssed.1978.0052
- Type: Article
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The open-circuit voltage Vo.c of m.i.s. cells has been reported and has been observed from our own experiments to be in the range of 400–525 mV for Al-SiO2-p-Si cells and in the range of 220–400 mV for Au-SiO2-n-Si cells. This is in contrast to the reported values of barrier heights for schottky diodes without an insulating layer. The difference in Voc is due to the change in the effective barrier height ømS. The change in ømS is assumed to be due to fixed positive charges in the thin oxide, and from the reported values of ømS the charge density in the oxide Qss/q has been calculated to be about 5 × 1012 cm−2.
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