Highly doped p+ regions by zinc diffusion utilizing metalorganic vapor‐phase epitaxy

Zinc‐diffusion doping of GaAs using metalorganic vapor‐phase epitaxy and DEZn as a dopant source is evaluated. The dependence of the diffusion profile on DEZn flow and diffusion time is presented. Typical zinc concentrations and depths obtained are 1019–1021 cm−3 and 40–200 nm, respectively. The largest concentration gradient obtained in this manner was four orders of magnitude in 500 A, and the highest zinc concentration was measured as 2×1021 cm−3 at a sample surface. A heterojunction bipolar transistor fabricated using zinc‐diffusion doping of the base and a regrown emitter showed an fmax of 50 GHz.