PHOTON-ASSISTED GROWTH OF NITROGEN-DOPED CDTE AND THE EFFECTS OF HYDROGEN INCORPORATION DURING GROWTH

Nitrogen doping in CdTe epilayers grown by photo-assisted molecular be am epitaxy was demonstrated using an rf plasma source. The effect of t he presence of atomic hydrogen during growth of undoped and nitrogen-d oped CdTe was investigated. The layers were characterized using photol uminescence spectroscopy (PL), Hall effect, secondary ion mass spectro scopy (SIMS), Fourier transform infrared spectroscopy, and atomic forc e microscopy. PL confirmed the incorporation of nitrogen as: accepters . While p-type carrier concentrations greater than 10(18) cm(-3) were easily obtained, SIMS measurements indicated that nitrogen was concent rated near the undoped-doped and epilayer-substrate interfaces which c omplicates interpretation of activation efficiency. Hydrogen incorpora tion was found to be enhanced by the presence of nitrogen. Infrared ab sorption measurements strongly suggested the formation of N-H complexe s. Hall measurements indicated that complexes are formed which are don or-like in nature. The presence of atomic hydrogen during growth radic ally changed the low temperature photoluminescence in both undoped and nitrogen-doped layers. Exciton-related luminescence was quenched at l ow temperature. Nitrogen-related donor-acceptor pair luminescence was also absent from the N-doped hydrogenated layers, consistent with comp lex formation. Copper (a cation-site acceptor) donor-acceptor pair lum inescence appeared to be enhanced by hydrogenation.