Highly efficient light emission from ZnS1−xTex alloys

ZnS1−xTex (0≤x≤1) single‐crystal alloy films were grown on GaAs and Si substrates by molecular beam epitaxy. Strong photoluminescence in the yellow to blue light region, with room‐temperature external quantum efficiencies of 2%–4% at an unoptimized excitation wavelength of 365 nm, was observed. The enhancement of luminescence was attributed to the presence of Te isoelectronic hole traps in the films. Strong bowing of the band‐gap energy as a function of composition x was also observed, with the minimum near x=0.7. The line width as well as the Stokes shift of the luminescence peak from the band edge were found to increase as Te composition decreases.