Diffusion of zinc in gallium arsenide with the participation isovalent impurities

The diffusion of Zn into GaAs in the presence of indium and phosphorus was studied. Zn diffusion was performed from the gas phase in a hydrogen flow under isothermal conditions (670 degrees C). A GaAs substrate was annealed in In and P vapors in a separate chamber. The annealing conditions simulated the memory effect of a MOVPE reactor and/or the cross-doping during the growth of multilayer structures based on III-V alloys. The aim of the current research was to study the effects of In and P on the Zn diffusion processes in GaAs. The results obtained by secondary-ion mass spectrometry show that, upon a pretreatment with In and P, both the incorporation efficiency and the diffusion rate of Zn increase. Measurements by Raman spectroscopy confirm the increase in the free-hole concentration in the sub-surface layers in pre-annealed samples. The influence of In and P on the diffusion process was observed at concentrations higher than 1017 cm(-3). Optical characterization reveals changes in the defect distribution in the GaAs samples. The changes of the recombination processes, caused by In and P, depend on the indium vs. phosphorus ratio. The effective Zn diffusion rate is controlled by this ratio. (C) 2015 Published by Elsevier B.V.