Photoluminescence of nitrogen-doped zinc selenide by photo-assisted MOCVD
Gillespie, Paul Matthew
Callahan, Daniel L.
Doctor of Philosophy
Zinc selenide is a wide band-gap (2.67 eV) II-VI compound semiconductor with potential use as a blue electro-optic device material. Problems with obtaining suitable p-type conductivity have limited device development. Zinc selenide epitaxial films, doped with nitrogen from NH$\sb3,$ have been grown on gallium arsenide substrates by laser-assisted metal organic chemical vapor deposition (MOCVD). The effect of nitrogen doping was investigated with and without direct surface irradiation incident on the surface from a broad-band light source. Low temperature (8 K) photoluminescence spectroscopy has confirmed the incorporation of nitrogen as a shallow acceptor by the presence of acceptor-bound-excitons and associated donor-acceptor-pair recombination emissions. The MOCVD growth parameters have been optimized based on the presence of characteristic features in the photoluminescence spectra. Growth rate mechanisms have been proposed for both laser-assisted MOCVD and direct-irradiation MOCVD. Simultaneous interaction of the two photo-assisted techniques show that direct irradiation of the surface does not enhance the growth rate under the laser-assisted condition. This confirms that direct surface irradiation growth mechanisms involve the interaction of photo-generated carriers with alkyl groups from the precursors.
Electronics; Electrical engineering; Condensed matter physics