P-doping with beryllium of long-wavelength InAsSb

The properties of low concentrations of Be as a p-dopant in InAsSb with a composition corresponding to absorption in the long wavelength infrared band were studied. Temperature-and magnetic field-dependent Hall effect data were analyzed with a multi-carrier model allowing extraction of the bulk hole concentration and mobility. The hole density exhibits a weak freeze-out with an activation energy of 3.2 meV. Density functional theory calculations indicate that Be favor the In sites as BeIn with an acceptor binding energy near the valence band maximum. The hole mobility increases monotonically as the temperature is lowered, showing an alloy scattering-limited value of about 1000 cm2 V-1 s-1 at 77 K and plateauing at around 3200 cm2 V-1 s-1 at 20 K. Temperature-dependent photoluminescence was measured up to 200 K and did not indicate any deleterious effects induced by the acceptors. A superlinear bandgap vs temperature behavior is tentatively interpreted as a band-filling effect, which is reduced with added concentrations of acceptors.