Growth and characterization of GaP and GaAs 1− xP x

Abstract

The minority carrier lifetime at low and high excitation densities was determined in VPE layers of GaP and GaAs ⩽0.2 P ⩾0.8. The lifetime at high excitation densities, having a value up to ∽350 ns, is one to two orders of magnitude larger than the lifetime at low excitation densities. It is shown that impurities are involved in some saturable killer centres dominating at low excitation densities. In the case of the largest values of the minority carrier lifetime and at a dislocation density of > 10 5 cm −2, the non-radiative recombination at high excitation densities is shown to occur at dislocations; at lower values of the minority carrier lifetime the killer action may be due to microprecipitates. These findings also hold for LPE layers of GaP. It is shown that by measuring the minority carrier lifetime as a function of temperature a discrimination is possible between killer action due to diffusion of minorities towards sinks like dislocations or microprecipitates and due to capture by a normal point-defect type recombination centre.