PREPARATION OF CDSSE-ZNS SUPERLATTICE, SRS, AND CDSSE-SRS SUPERLATTICE BY HOT-WALL EPITAXY, AND APPLICATIONS TO ELECTROLUMINESCENT DEVICES

CdSSe (manganese-doped, E(g) = 1.9-2.5 eV, lattice constant a = 6.05-5 .8A)-ZnS (Eg = 3.56 eV, a = 5.41A) superlattices, SrS (cerium-doped, E (g) = 4.4 eV, a = 6.02A) layers, and CdSSe-SrS (cerium-doped) superlat tice layers have been prepared by hot-wall epitaxy, and the properties and the electroluminescent device characteristics of the active layer s are reported. For the superlattices with ZnS, the maximum luminance was 800 cd/M2 at an applied sinusoidal voltage (V(o-p) = 200 V) with f requency 1kHz, and the wavelength of the spectral peak was 610 nm due to the large strain caused by the lattice mismatch (8-15%) between the CdSSe and ZnS layers. The maximum luminance and Comisson Internationa le de Enluminure (CIE) chromaticity of CdS(Mn)-ZnS superlattices and C dSe(Mn)-ZnS superlattice devices were 557cd/m2 and (x,y) = (0.58, 0.41 ) and 982 cd/m2 and (0.61, 0.38), respectively. For superlattices with SrS, the maximum luminance of the device with the SrS (cerium-doped) active layer was nearly 700 cd/m2 at a voltage of 340 V. Blue electrol uminescent emission was observed in the photon wavelength region less than 450 nm, due to carriers dropping into the quantum wells of the de vice with the CdSSe-SrS superlattice active layer.