Effect of growth rate on surface morphology of heavily carbon-doped InGaAs

Carbon-doped InGaAs was grown at two growth rates by chemical beam epitaxy using carbon tetrabromide as the dopant precursor. Surface roughness was me asured using atomic force microscopy. Step-flow growth was observed for und oped InGaAs but a roughening of the surface and loss of step-flow growth oc curred at high carbon-doping levels, possibly due to etching effects. The p oint at which the surface grew rough also corresponded to an increase in th e variability of carbon. as reported by secondary ion mass spectrometry. In creasing the growth rate allowed the to remain smooth at higher carbon conc entrations. The hole concentration saturated for samples grown at both grow th rates. Carrier activation was slightly better in samples grown at a high growth rate. The ability to maintain good surface morphology at elevated c arbon concentrations is critical for the fabrication of high frequency hete rojunction bipolar transistors. (C) 2001 American Vacuum Society.