The optoelectronic properties of the II-IV-V2 semiconductor ZnSnP2 are studied as a function of the cooling rate of the crystal growth melt. The structure of the material, as studied by x-ray diffraction, is seen to change from chalcopyrite to sphalerite as the cooling rate is increased. Photoelectrochemical measurements show that the bandgap of the material decreases from 1.64 eV for the chalcopyrite to 1.25 eV as the structure approaches sphalerite. The 119Sn Mössbauer spectroscopy shows both an isomer shift and a broadening of the 119Sn resonance as a result of new tin environments produced by disordering of zinc and tin sites at the faster cooling rates. The 31P solid-state nuclear magnetic resonance spectroscopy clearly shows new resonances associated with the additional phosphorus environments produced by metal site disordering. A model based on zinc and tin site exchange with the introduction of compensating donor and acceptor states is proposed and discussed.

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Several organic and inorganic materials have been tested for possible incorporation into a sensing array in order to add elemental mercury vapor to the suite of chemical species detected. Materials have included gold films, treated gold films, polymer-carbon composite films, gold-polymer-carbon composite films and palladium chloride sintered films.

Photocurrent spectroscopy is used to measure the polarization dependence of optical transitions in β-ZnP2 and to identify an impurity state. A large polarization dependence was measured in the photocurrent spectrum with the light polarized parallel or perpendicular to the c axis of a β-ZnP2 crystal. Structure observed in the spectra was attributed to polaritons and, in the n-type samples, to an impurity level associated with tin.