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Journal of Vacuum Science & Technology A, Vol.17, No.1, 1-8, 1999
Homoepitaxial growth of CdTe on vicinal CdTe(100) surfaces: Reaction kinetics and mechanism
Homoepitaxial films of CdTe were grown on vicinal CdTe(100) surfaces using Cd(CH3)(2) and Te(C3H7)(2) precursors in an atmosphere of H-2. The vicinal CdTe(100) substrates were misoriented by 0 degrees, 2 degrees, 4 degrees, 6 degrees, and 8 degrees from the (100) direction towards the (111)(Te) direction and thus had systematically increasing step densities. The CdTe films grown on these surfaces were single crystalline and epitaxial but had gross surface morphologies that depended on the misorientation of the substrate. Films grown on the CdTe(100)-0 degrees and CdTe(100)-8 degrees substrates were rough while those grown on the CdTe(100)-4 degrees substrate were smooth. The kinetics of film growth were studied through measurements of the overall film growth rates and measurements of precursor adsorption/ desorption kinetics. Film growth rates were weakly dependent on the degree of substrate misorientation, increasing slightly with increasing step density. Although the step density determines film morphology, the steps are not active sites for decomposition of precursors and do not participate in the rate determining steps of the growth mechanism. Studies of the surface chemistry of the Cd(CH3)(2) and Te(C3H7)(2) precursors show that they are reversibly adsorbed on the vicinal CdTe(100) surfaces, which is quite different from precursor surface chemistry on III-V semiconductors where adsorption tends to be irreversible.
Keywords:VAPOR-PHASE EPITAXY;CADMIUM TELLURIDE;MBE GROWTH;SUBSTRATEMISORIENTATION;DEPOSITION;CHEMISTRY;GAAS(100);GAAS;DIETHYLZINC;MORPHOLOGY