Double doping: A method to decrease dislocation densities in LEC InP crystals

The authors report on the growth of low-dislocation density low-carrier concentration p-type InP via codoping with CdTe. Four crystals were grown by the liquid encapsulated Czochralski (LEC) technique. The results of electrical and analytical studies suggest that both cadmium and tellurium undergo some chemical reactions before pulling, so that only a minor fraction of the added impurities is available for doping. The effectiveness of this codoping in terms of dislocation density reduction has been confirmed by the structural investigations carried out on the four crystals with low free carrier concentrations. The role of multiple doping as a strategy for dislocation reduction is discussed