The low hole mobility of p-type compound semiconductors prevents the realization of high performance III-V-based field-effect transistor complementary circuits. Recently, it was shown that incorporation of compressive strain in the channel layer could increase the in-plane two-dimensional hole gas (2DHG) mobility of antimonide-based quantum well (QW) materials . Beryllium (Be) was used as the dopant in previous studies, but Be would easily diffuse out into adjacent layers during the growth process. The channel layer may thus have higher background doping with increased impurity scattering. In this research, we used carbon as the p-type dopant to avoid dopant diffusion. The growth was carried out using gas-source molecular beam epitaxy, and the p-type doping was achieved using a carbon-tetrabromide source via an ultra-high vacuum leak valve. The strained In(x)Ga(1-x)Sb QW structure was metamorphically grown on semi-insulating InP substrates, using Al(x)Ga(1-x)Sb/AlAsSb as the composite barrier layers. High-resolution X-ray diffraction (HRXRD) rocking curve of the as-grown sample showed the AlSb buffer layer was 98% relaxed and the indium composition in the strained In(x)Ga(1-x)Sb QW was 0.3. The corresponding compressive strain in the In(x)Ga(1-x)Sb QW is 1.2%. With optimization of growth conditions and modification of the barrier layer, the room-temperature hole mobility of an In(0.3)Ga(0.7)Sb QW reference structure (without carbon delta-doping) increased from 360 to 600 cm^2/V-s. Compared with pure GaSb QW structure, the hole mobility improvement is about 66% at a similar sheet carrier concentration. Carbon delta-doping was also proved to be effective, which could increase the sheet carrier concentration to 4.1E11/cm^2 with three-second flow of carbon-tetrabromide. The hole mobility decreased to 400 cm^2/V-s with the increasing carrier concentration. The results suggest that the doping concentration of the In(0.3)Ga(0.7)Sb channel can be easily controlled using carbon-tetrabromide as the delta-doping source.
 Bennett. B et al. Appl. Phys. Lett. 91, 042104 (2007)