Hydrogen in carbon-doped GaAs base layer of GaInP/GaAs heterojunction bipolar transistors

Hydrogen incorporation into heavily carbon-doped GaAs grown by metal-organic vapour phase epitaxy using carbon tetrabromide (CBr4) has been studied. In the base layer of as-grown GaInP/GaAs heterojunction bipolar transistors (HBTs), about 20% of the carbon acceptors are found to be passivated by hydrogen. The outdiffusion of this hydrogen during an ex situ annealing at 450 °C in nitrogen, which is effective for carbon-doped single layers, is blocked by n-type capping layers in HBTs. An in situ annealing step was found to be suitable to reduce the acceptor passivation in HBTs to about 10%.