Electrical and Photoluminescence Studies of {LT-GaAs/GaAs:Si} Superlattices Grown by MBE on (100)- and (111)A-Oriented GaAs Substrates

Abstract

The results of studying semiconductor structures proposed for the first time and grown, which combine the properties of LT-GaAs with p-type conductivity upon doping with Si, are presented. The structures are {LT-GaAs/GaAs:Si} superlattices, in which the LT-GaAs layers are grown at a low temperature (in the range 280–350°C) and the GaAs:Si layers at a higher temperature (470°C). The p-type conductivity upon doping with Si is provided by the use of GaAs(111)A substrates and the choice of the growth temperature and the ratio between As₄ and Ga fluxes. The hole concentration steadily decreases, as the growth temperature of LT-GaAs layers is lowered from 350 to 280°C, which is attributed to an increase in the roughness of interfaces between layers and to the formation of regions depleted of charge carriers at the interfaces between the GaAs:Si and LT-GaAS layers. The evolution of the photoluminescence spectra at 77 K under variations in the growth temperature of LT-GaAs is interpreted as a result of changes in the concentration of Ga_As and V_Ga point defects and Si_Ga–V_Ga, V_As–Si_As, and Si_As–Si_Ga complexes.