CARBON DOPING OF INGAAS IN SOLID-SOURCE MOLECULAR-BEAM EPITAXY USING CARBON TETRABROMIDE

Carbon tetrabromide was used to dope (In,Ga)As layers lattice matched to InP grown by solid-source molecular beam epitaxy. The maximum hole density depended on substrate temperature. A hole concentration as high as 7.5 x 10(19) CM-3 was achieved at a substrate temperature of 450-degrees-C with reduced As2 flux. Variations in arsenic flux intensity were found to have little effect on the doping density. Hole mobility was comparable to the mobility of Be-doped material grown in our MBE system and to the mobility Of CCl4-doped material grown elsewhere. We observed a short-term doping memory effect which we attribute to desorption of CBr4 from growth chamber internal surfaces due to radiant heat from column III ovens. (In,Al)As/(In,Ga)As Npn heterojunction bipolar transistors fabricated using CBr4 doping for the (In,Ga)As base layer with p = 2 X 10(19) cm-3 exhibited a dc current gain of eight.