In this paper, various methods for characterization of semiconductor charge carrier lifetime are reviewed and an optical technique is described in detail. This technique is contactless, all-optical and based upon measurements of free carrier absorption transients by an infrared probe beam following electron-hole pair excitation by a pulsed laser beam. Main features are a direct probing of the excess carrier density coupled with a homogeneous carrier distribution within the sample, enabling precision studies of different recombination mechanisms. The method is capable of measuring the lifetime over a broad range of injections (10 13 -10 18 cm -3 ) probing the minority carrier lifetime, the high injection lifetime and Auger recombination, as well as the transition between these ranges. Performance and limitations of the technique, such as lateral resolution, are addressed while application of the technique for lifetime mapping and effects of surface recombination are also outlined.Results from detailed studies of the injection dependence yield good agreement with the Shockley-Read-Hall theory, whereas the coefficient for Auger recombination shows an apparent shift to a higher value, with respect to the traditionally accepted value, at carrier densities below 2×10 17 cm -3 . Data also indicate an increased value of the coefficient for bimolecular recombination from the generally accepted value. Measurement on an electron irradiated wafer and wafers of exceptionally high carrier lifetimes are also discussed within the framework of different recombination mechanisms.
Structural, morphological, and defect properties of metamorphic In0.7Ga0.3As/GaAs0.35Sb0.65 p-type tunnel field effect transistor structure grown by molecular beam epitaxy J. Vac. Sci. Technol. B 31, 041203 (2013); 10.1116/1.4812793 Effect of indium surfactant on stress relaxation by V-defect formation in GaN epilayers grown by metalorganic chemical vapor deposition J. Appl. Phys. 108, 093511 (2010); 10.1063/1.3487955Strain relaxation and surface roughness of In x Al 1 − x As graded buffer layers grown on InP for 6.05 Å applications J.Growth of room-temperature "arsenic free" infrared photovoltaic detectors on GaSb substrate using metamorphic InAlSb digital alloy buffer layers Metamorphic growth of In 0.15 Ga 0.85 Sb on a GaSb substrate is reported using In x Ga 1−x Sb buffer layers compositionally graded in steps of x = 0.03. All layers were grown using gas source molecular beam epitaxy with a fixed Sb flux providing an excess group-V overpressure. The growth temperature was varied from 450 to 540°C. X-ray diffraction analysis was used to determine the effect of growth temperature on relaxation and residual strain. As the growth temperature is increased, cross-sectional transmission electron microscopy ͑TEM͒ shows that the number of dislocations threading through the metamorphic layer are reduced. Plan-view TEM yields misfit dislocation density around 10 8 cm −2 and from atomic force microscopy, the surface roughness is ϳ1 nm. Both surface roughness and dislocation density improves with higher growth temperature. Finally, p-i-n homojunction diodes of various sizes on metamorphic layers were demonstrated.
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