The growth and characterization of CdTe epitaxial layers on CdTe and InSb by metalorganic chemical vapor deposition

Abstract

Epitaxial layers of CdTe were grown on CdTe and InSb substrates by metalorganic chemical vapor deposition using dimethylcadmium and dimethyltelluride as alkyl sources. Specular CdTe layers were grown on InSb at temperatures between 350 and 375 °C with serious out-diffusion of In from substrates. Dimethyltelluride is the controlling species of this growth system. Typical growth rates were 4 to 7 μm/h. Low-temperature photoluminescent measurements revealed the superior quality of epitaxial layers grown on CdTe substrates. The bound-exciton emission at 1.590 eV and the band-edge emission at 1.548 eV are the dominant peaks. Homostructure CdTe epitaxial layers grown between 330 and 410 °C possess the best surface morphology. Hole concentrations in the 1013-cm−3 range and a carrier mobility over 100 cm2/V sec were observed in these layers at 77 K. The highest hole mobility is 555 cm2/V sec in the sample grown at 400 °C. Layers grown outside this range show n-type conductivity with deteriorated electron mobilities and photoluminescent spectra.