ZnCdTe/ZnTe Light Emitting Diodes with MgSeTe/ZnTe Superlattice Layers Grown on ZnTe Substrates by Molecular Beam Epitaxy

MgSeTe/ZnTe superlattices were proposed as carrier-confinement layers for high-performance yellow-green light emitting diodes (LEDs) on ZnTe substrates for the first time. ZnCdTe/ZnTe LEDs consisting of ZnCdTe quantum well active and ZnTe cladding layers were fabricated by molecular beam epitaxy incorporating the MgSeTe/ZnTe superlattices between the active and the cladding layers. The LEDs were characterized by electro-luminescence (EL) measurements at room temperature. As a result, a narrow yellow emission at 578 nm with the FWHM value of 25.0 meV was observed in the EL measurements. Comparing LEDs with and without the superlattices, no influence on emission spectra was observed even by incorporating the superlattices. On the other hand, the external quantum efficiency of the LEDs with the superlattice was drastically improved by 5.5 times. This result indicated that the superlattice confinement layers were very effective to increase the emission efficiency of the LEDs.