LIGHT IRRADIATION EFFECTS ON IMPURITY DOPING IN ZNSE BY PHOTOASSISTEDMOLECULAR-BEAM EPITAXY

We have investigated light irradiation effects on donor and acceptor i mpurity doping in photoassisted MBE growth of ZnSe. Li and N were chos en as acceptor impurities, and Ga and Cl as donor impurities. A He-Cd laser with a wavelength of 441.6 nm (250 MW/cm2) was used as an irradi ation source. Bound exciton emissions of neutral acceptor (I-1(S)) or neutral donor (I2) were observed in photoluminescence spectra. The bin ding energies of I-1(S) and I2 of the irradiated epilayers are the sam e as those of the nonirradiated epilayers. The intensities of bound ex citon emissions of Li, N and Cl were decreased by the irradiation, and that of Ga was increased. It was revealed that the changes in the int ensities were not attributable to the surface-stoichiometry change by the irradiation. The increase and decrease in the intensities are disc ussed on the basis of photodesorption of impurity atoms during photoas sisted MBE growth of ZnSe.