Carbon doping in InGaAsSb films on (001) InP substrate using CBr4 grown by metalorganic chemical vapor deposition

This paper reports on carbon (C) doping in InGaAsSb grown on (001) InP substrates by the metalorganic chemical vapor depositions (MOCVD) method using carbontetrabromide (CBr4). The influence of the CBr4 flow rate on the relationships between InGaAsSb alloy compositions and the molar flow ratio of III-V-atom precursors was investigated in C-doped InGaAsSb films. We found that there is nonlinear dependence of the solid In content on the molar flow ratio of group-III precursors for C-doped InGaAsSb. Thermodynamic calculations of the reactions in the InGaAsSb growth process reveal that the characteristic nonlinear dependence is due to the etching reactions of group-III elements with hydrogen bromide, which is generated by CBr4 decomposition. The solid Sb content of both undoped and C-doped InGaAsSb films decreases with increasing molar flow ratio of In precursors due to the preferential incorporations of InAs in In-rich antimonide compounds. On the basis of the obtained knowledge, we have succeeded in growing C-doped InGaAsSb film with a high hole concentration of over 1.0×1019 cm−3, which is useful for the base layer of InP-based heterojunction bipolar transistors. As in C-doped GaAsSb, the effect of hydrogen passivation of C-acceptors in C-doped InGaAsSb is almost negligible.