Thermionic currents and acceptor diffusion in p+-In0.53Ga0.47As/n-InP heterojunctions

p +-In0.53Ga0.47As/n-InP heterojunctions grown by liquid-phase epitaxy have been investigated through I-V and I0(T) measurements. It is shown that the injection of electrons across the heterointerface is well described by a thermionic emission model characterized by a barrier height which is strongly affected by p-type dopant diffusion. Heterojunction bipolar transistors with Schottky collectors were used as tools to measure the injection current in as-grown p+-In0.53Ga0.47As/n-InP diodes, and the results were compared to the predictions of the thermionic emission model. In this way, the relative diffusivity in InP at 600 °C of three p-type dopants, Mn, Mg, and Be, have been evaluated. The results can be summarized as follows: DBe/DMn≊20, DMg/DBe≊1. The effects of postgrowth heat treatments on the observed barrier height are also discussed.