| The thin films, 0.2 - 4 micrometers, of copper indium diselenide analysed in this study were prepared by spray pyrolysis from solutions of indium chloride, N,N-dimethylselenourea and either cuprous chloride or cupric chloride. Solution pH was varied by adding ammonium hydroxide hydrochloride to cuprous chloride solutions or HCl to cupric chloride solutions. Solutions were sprayed on glass, Mo/glass, or CdS substrates at temperatures from 225(DEGREES)C to 350(DEGREES)C. Heterojunctions were fabricated in the backwall configuration from spray-pyrolysed CdS, and in the reverse backwall configuration from evaporated CdS.;X-ray diffraction, scanning electron microscopy, optical absorption and reflectivity, and resistivity and Hall measurements were used to evaluate film properties. I-V analysis, AM1.5 solar efficiency, and spectral response were used to evaluate device performance.;Lower pH, higher Cu:In ratio and higher substrate temperature were found to decrease the driving force for deposition thus increasing the grain size and the degree of 112 orientation. Cupric chloride and non-neutralized cuprous chloride solutions deposited at 300(DEGREES)C produced relatively planar films, with cupric chloride producing slightly larger grains of one micrometer in size. Spray conditions which resulted in poor crystallinity and grain size were also found to yield poor optical behavior.;Phases other than chalcopyrite copper indium diselenide were found to occur over a wide range of growth conditions. The nucleation of these phases was found to depend strongly on temperature, substrate, and stoichiometry and pH of the starting solution. Conditions for producing chalcopyrite single phase high resistivity material, necessary for efficient solar energy conversion, were determined.;Decreasing the Cu:In ratio or increasing the pH or substrate temperature was found to increase compensation resulting in higher resistivities, lower mobilities, and band tailing. This compensation is believed to be due to increased indium incorporation.;It was found that devices prepared from multi-phase copper indium diselenide exhibited low Jsc and Voc values, and degraded with heat treatment. Reverse backwall devices prepared from chalcopyrite single phase high resistivity copper indium diselenide suffered from severe shorting due to pinholes. Without a back contact, this configuration produced a Voc of 0.558 V. |
