Carbon has gained wide acceptance as a p-type dopant for GaAs-based device structures due to its low atomic diffusivity. Carbon doping of InGaAs, however, is complicated by the amphoteric nature of C and difficulty in incorporating C efficiently during epitaxial growth. We have achieved hole concentrations as high as 7x1019 cm−3 in CC14-doped InGaAs grown at low temperature by MOCVD. Growth-related issues include the effect of CCl4 on the alloy composition due to etching during growth, and the incorporation of hydrogen, which passivates the C acceptor and reduces the hole concentration during growth and during the post-growth cool-down. The effect of H passivation on minority carrier transport has been characterized by the zero-field time-of-flight technique. High frequency InP/InGaAs HBTs with a C-doped base have been demonstrated with ft = 62 GHz and fmax = 42 GHz, which is comparable to the best performance reported for MOCVD-grown InP/InGaAs HBTs.

A shallow acceptor-like defect labeled “A” is frequently incorporated in molecular beam epitaxial GaAs. We report here anomalous photoluminescence effects that are induced by this defect. With increasing concentration of the “A” defect: (1) neutral and ionized donor-bound exciton peaks disappear almost completely even for donor concentration as high as 7×1014 cm-3 and compensation ratio ND/NA≈0.3; (2) a new, sharp line emerges at 1.5138 eV, and (3) the relative intensity and line shape of the free exciton transition change dramatically. These observations are discussed in the perspective of previous reports, where similar effects were, in our opinion, misinterpreted.