Optical properties of silicon-doped (100) GaAs layers grown by molecular-beam epitaxy

The photoluminescence spectra of (100) GaAs layers, both undoped and doped with silicon, is investigated at T = 77 K. It is found that along with the B-band, which corresponds to interband radiative recombination, the spectra of doped layers also exhibit a so-called Si-band located near hv similar or equal to 1.4 eV. In multilayer delta-doped structures, an additional band appears in the region h v similar or equal to 1.47-1.48 eV, which is called here the delta-band. The dependence of the energy positions, intensities, and shapes of these photoluminescence bands on the doping dose N-Si, laser excitation power, and temperature are investigated. It is shown that the Si-band is caused by optical transitions between the conduction band and a deep acceptor level (similar to 100 meV) connected with Si atoms on As sites. It is also established that the dependences of the shape and intensity of the delta-band on temperature and photoluminescence excitation power are identical to the corresponding dependences for the B-band. The behavior of the delta-band in the photoluminescence spectra is viewed as evidence of quantum-well effects in the delta-doped structures. (C) 1998 American Institute of Physics. [S1063-7826(98)00909-0].