Electrical and optical properties of Si doped GaAs (631) layers studied as a function of the growth temperature

摘要

The Si incorporation into GaAs layers grown by molecular beam epitaxy on GaAs (631)A substrates as a function of the growth temperature was studied. Atomic force microscopy measurements showed an evolution of the samples surface from hillocks structures to flat and finally uniform corrugation as the temperature was increased from 450 to 660 ℃ Hall measurements performed at room temperature revealed that conduction type conversion from n- to p-type took place in the range of growth temperature from 480 ℃ to 500 ℃. Above 500 ℃ both the p-carrier concentration in the films and the carriers' mobility remain nearly unaffected by the temperature. Before the onset of the conduction type conversion, the electrical properties changed dramatically. It is demonstrated that the electrical properties are not related with the surface topography. Photoluminescence spectra of the films showed optical transitions associated with the occupancy of Si on Ga and As sites, and therefore transitions related to donor and acceptor levels. For the most compensated samples, PL spectra are dominated by donor-acceptor (D-A) transitions, whose characteristics were studied by excitation power intensity experiments.