LUMINESCENCE OF UNDOPED AND CHLORINE-DOPED ZN1-XCDXSE AND ZN1-XMGXSYSE1-Y LAYERS OBTAINED BY MOLECULAR-BEAM EPITAXY

The temperature dependences of the edge photoluminescence of undoped a nd chlorine-doped layers Zn1-xCdxSe (0 < x < 0.2) and Zn1-xMgxSySe1-y (0 < x < 0.05, 0 < y < 0.25) grown by the method of molecular-beam epi taxy on GaAs (100) substrates were investigated. It was shown that com position fluctuations in the solid solution, which are strongest for t he ZnSeySe1-y(Zn1-xCdxSe) layers with a high S(Cd) content, substantia lly broaden the excitonic luminescence line. At liquid-helium temperat ures exciton localization on composition fluctuations results in a hig her integral intensity of the photoluminescence of solid solutions tha n in pure ZnSe layers with low excitation densities. At 77 K delocaliz ation of excitons and carriers occurs, and consequently the integral i ntensity of edge photoluminescence decreases substantially. Moderate d oping with chlorine (10(17)-10(18) cm(-3)) produces a giant increase i n the intensity of edge photoluminescence in ZnSe and ZnSySe1-y layers . Injection lasers with quantum wells in the system ZnSe-ZnCdSe, which operate at 77 K in the pulsed mode (the threshold current density is equal to 600 A/cm(2)), have been developed. Structures with ZnSSe emit ters whose lattice parameter is matched with that of the GaAs substrat e were used to obtain pulsed room-temperature lasers. (C) 1996 America n Institute of Physics.