Optical and Electrical Characterization of Bulk Grown Indium-Gallium-Arsenide Alloys

Advances in crystal growth techniques have allowed increased quality in growth of bulk ternary InxGa1-xAs. Here, the optical and electrical properties of samples grown through the vertical Bridgman (or multi-component zone melting growth) method have been investigated through photoluminescence spectroscopy and Hall effect measurements. Indium mole fractions varied from 0.75 for 1. Hall effect measurements at temperatures ranging from 10 to 300 K revealed moderate n-type doping with carrier concentrations ranging from 1.5 to 9.6 10 16 cm -3 at 10 to 15 K. Carriers from deep donor levels became appreciable between 50 and 100 K. Hall mobility increased with rising indium content, and mobility values at 15 K ranged from 1.5 10 4 cm 2/(V's) for In0.75Ga0.25As to 3.5 10 4 cm 2/(V's) for InAs. Mobility variation with temperature showed ionized impurity scattering to be dominant at low temperatures with optical phonon scattering becoming dominant near 100 K. Laser excitation power dependent photoluminescence measurements were performed at 12 K, and temperature dependent photoluminescence measurements were performed at temperatures ranging from approximately 12 to 140 K. Photoluminescence measurements showed band-to-band and donor-acceptor pair transitions. 12 K band-to-band photoluminescence peak positions loosely followed predicted band gaps, and position dependent photoluminescence measurements revealed varying degrees of uniformity across the samples studied.