Optoelectronic properties of 2-D and 3-D-grown GaInNAs//GaAs QW light emitting diodes and laser diodes
The optoelectronic properties of light emitting diodes (LEDs) and laser diodes (LDs) based on GaInNAs/GaAs quantum wells (QWs) grown under two-dimensional (2-D) and three-dimensional (3-D) conditions are compared. In spite of the longer wavelength, the 2-D LED shows better luminescence properties than the one with island formation. The broadening of the photocurrent spectra and the Stokes shift are used to analyse carrier localisation effects. The emission from localised states is found to impact the electroluminescence of the 3-D device even at room temperature, while it does not significantly influence the high-temperature emission of the 2-D LED. From a detailed analysis of the low-temperature electroluminescence as a function of injected current, nonradiative recombination is found to be the main carrier recombination mechanism in a wide range of currents in the 3-D LED, while it is very small in the 2-D case. Consequently, defect formation seems to be closely related to the 3-D growth, limiting laser emission in these structures. These results suggest that 2-D-grown GaInNAs/GaAs QWs may be more desirable for achieving laser emission at long wavelengths.
