Cubic ZnCdS Lattice-Matched to GaAs: A Novel Material for Short-Wavelength Optoelectronic Applications

Abstract

We propose cubic Zn 1- x Cd x S epilayers lattice-matched to GaAs ( x ∼0.58) as a new candidate for short-wavelength optoelectronic applications. This material is expected to possess a wide bandgap corresponding to the blue-to-purple spectral region and a mismatch in the thermal expansion coefficient smaller than that of the ZnSSe/GaAs system (1/4 of the latter). The problem lay in whether we could obtain a cubic structure, since only a hexagonal structure has been prepared for ZnCdS. In this study, we report on the successful growth of a cubic material by organometallic vapor-phase epitaxy. The nearly lattice-matched epilayers ( x ≃0.50∼0.65) showed good crystallographic properties and strong blue or purple photoluminescence both at 4.2 K and at room temperature.