Electrical and photoluminescence studies of $\{\mathrm{LT}-\mathrm{GaAs/GaAs} : \mathrm{Si}\}$ superlattices grown by MBE on (100)- and (111)A-oriented GaAs substrates

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 $\{\mathrm{LT}-\mathrm{GaAs/GaAs} : \mathrm{Si}\}$ superlattices, in which the LT-GaAs layers are grown at a low temperature (in the range 280–350$^{\circ}$C) and the GaAs:Si layers at a higher temperature (470$^{\circ}$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 As$_4$ and Ga fluxes. The hole concentration steadily decreases, as the growth temperature of LT-GaAs layers is lowered from 350 to 280$^{\circ}$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$_{\mathrm{As}}$ and $V_{\mathrm{Ga}}$ point defects and Si$_{\mathrm{Ga}}$–$V_{\mathrm{Ga}}$, $V_{\mathrm{As}}$–Si$_{\mathrm{As}}$, Si$_{\mathrm{As}}$–Si$_{\mathrm{Ga}}$ complexes.