N- type doping of gallium antimonide and aluminum antimonide grown by molecular beam epitaxy using lead telluride as a tellurium dopant source

Lead telluride was used as a “captive” source of tellurium (Te) for the n-type doping of gallium antimonide (GaSb) and aluminum antimonide (AlSb)grown by molecular beam epitaxy. Controllable carrier concentrations from 1.2 x 10¹⁶ to 1.6 x 10¹⁸ cm^-3 were obtained. High room-temperature Hall mobilities of 4200 cm²/V · s were measured for the low-doped GaSb samples. In the growth temperature range of interest, doping ef-ficiencies are approximately 50% of those in GaAs. For GaSb, SIMS data show that the Te incorporation decreases significantly at growth temperatures above 500° C. How-ever, in AlSb, there is no significant reduction in the incorporation of Te up to at least 650° C. In contrast, the Te incorporation into AlSb decreases at low temperatures. There is also some evidence of surface segregation in AlSb. Contrary to other doping studies, increasing the Sb : Ga flux ratio was found to reduce the Te incorporation.