PHOTO-LUMINESCENCE IN ZNSE GROWN BY LIQUID-PHASE EPITAXY FROM ZN-GA SOLUTION

Photoluminescence has been studied of epitaxial ZnSe layers grown from a pure Zn or a Zn-Ga alloy solution on ZnSxSe1-x (0≤x≤1) single-crystalline substrates. Intense blue emission bands at room temperature have been observed in the layers grown from a Zn-Ga alloy solution. The spectrum of the layer at 4.2 K generally consists of a strong emission line due to radiative recombination of excitons bound to the neutral donor, I 2, an associated donor-acceptor pair emission band with LO-phonon replicas, and a deep-level emission, i.e., the so-called SA emission band. The effect of Ga on the emission spectrum is to greatly increase the intensity of the blue part of the spectrum. On the basis of the comparison between the experimental results and theoretical calculations, it is tentatively proposed that the blue emisison bands at room temperature originate from the radiative recombination due to band-to-band transition.