Metalorganic molecular beam epitaxy of carbon‐doped heterostructures and InP/Ga0.47In0.53As heterostructure bipolar transistors using carbontetrabromide (CBr4) as the dopant source is reported. Secondary ion mass spectrometry show H incorporation associated with the carbon doping. Hall data for as‐grown and postgrowth annealed samples showed a clear increase in doping only for samples grown at the lowest temperature, 450 °C, and higher doping levels. An increase in the mobility, however, was measured for nearly all samples after annealing, indicating that the neutral C–H complexes most likely contribute to majority carrier scattering. The gain variation for various devices with base thickness,WB, and base doping,p, was found to be nearly proportional to 1/(WB×p)2consistent with diffusive base transport and Auger dominated recombination in the heavily doped base region. It was also observed that in devices where the C‐doped base was grown at temperatures ≳500 °C, the gain was shifted to much lower values possibly indicating a reduced electron carrier lifetime. ©1995 American Institute of Physics.