Growth and characterization of

Abstract

In0.2Ga0.8Sb epitaxial layers and thermophotovoltaic (TPV) device structures have been grown on GaSb and GaAs substrates by metalorganic vapor phase epitaxy (MOVPE). Control of the n-type doping up to 1×1018 cm−3 was achieved using diethyltellurium (DETe) as the dopant source. A Hall mobility of greater than 8000 cm2/Vs at 77K was obtained for a 3×1017 cm−3 doped In0.2Ga0.8Sb layer grown on high-resistivity GaSb substrate. The In0.2Ga0.8Sb epilayers directly grown on GaSb substrates were tilted with respect to the substrates, with the amount of tilt increasing with the layer thickness. Transmission electron microscopy (TEM) studies of the layers showed the presence of dislocation networks across the epilayers parallel to the interface at different distances from the interface, but the layers above this dislocation network were virtually free of dislocations. A strong correlation between epilayer tilt and TPV device properties was found, with layers having more tilt providing better devices. The results suggest that the dislocations moving parallel to the interface cause lattice tilt, and control of this layer tilt may enable the fabrication of better quality device structures.