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A process is reported for preparation of thin films of copper indium diselenide (CIS). This process involves two steps: (a) formation of Cu2In2O5 by spray pyrolysis and (b) reaction of Cu2In2O5 with selenium vapor to form CIS. The purity of the CIS prepared by this method can approach that of the material prepared by vacuum deposition methods because highly purified water and nitrate salts can be used in the spray pyrolysis step, and the purity of the selenium used in the second step can be identical to that used in any of the vacuum processes. This two-step process appears to have general applicability; we have been able to prepare a variety of sulfides and tellurides in addition to selenides. The advantage of this process is that any metal ion added to the spray solution is incorporated in the oxide and remains in the selenide after the selenization. Comparison of the Cu/In ratios of the selenide films with those of the precursor oxide films shows that there was a slight decrease in the copper content when the oxide was converted to the selenide. The consistency of the composition of the films prepared at 400 °C is comparable to that of films prepared by the other methods such as thermal processing of elemental layers and reactive sputtering of Cu and In with selenium vapor. Auger composition studies indicated that selenium substitution occurred stepwise. The x-ray-diffraction data for CIS were consistent with a chalcopyrite phase. The data for the resistivity and Hall-effect measurements at room temperature indicated a marked dependence of the resistivity and the hole density on the Cu/In atomic ratio. When this ratio was around 1.45, the resistivity had low values around 30 Ω cm, and the hole density was in the 1017 cm−3 range. A direct band gap of 0.95 eV was determined from the optical-absorption spectrum of this material.

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N,N-dimethylethylenediamine were used instead. Orange yellowish needles (0.15 g, 75%) resulted after etheral workup. 2((CHz)2N+(Me)3). The procedure for preparing 2(Py+Me) was followed except that 20.9 mg (0.078 mmol) of ((CH,),N(CH,),) and 67 ML (0.78 mmol) of dimethyl sulfate were used. A pale white precipitate (52 mg, 80%) wm collected. IR (Kl3r) 3080,cm-'. 'H NMR (D20) 8.73 (4 H, s), 4.64 (4 H, t, J = 7.7), 3.67 (10 H, m), 3.29 ppm (18 H, br 9). FAB MS (MNBA matrix) calculated for CXH30N4O4 438.2260, observed (M+) 438.2257. HPLC retention time 3.53 min; flow rate 0.5 mL/min. 2((CH2),N(CH3),). The procedure for 2(Py) was used except that 0.101 g (0.38 mmol) of anhydride and 142 p L (1.13 mmol) of N,N-dimethylpropylenediamine were used instead. A bright yellowish powder (0.09 g, 54%) was isolated after workup.2((CH2)3N+(Me)3). The procedure for preparing 2(Py+CH3) was followed except that 48.7 mg (0.1 mmol) of 2(CH2)3-N(CH3)2 and 106 pL (1.1 m o l ) of dimethyl sulfate were used. A pale white precipitate (48 mg, 70%) was collected. cm-' . ' H NMR (D20) 8.63 (4 H, s), 4.23 (4 H, t, J = 7.71, 3.68 (6 H, m), 3.51 (4 H, t, J = 7.7), 3.12 (18 H, br s), 2.26 (4 H, m). FAB MS (MNBA matrix) calculated for C26H34N404 466.2572, observed (M+) 466.2591. HPLC retention time 3.58 min; flow rate 0.5 mL/min.A new process involving two steps has been developed to prepare thin-film InzSe3. The first step is formation of indium oxide by spray pyrolysis of an aqueous solution of indium nitrate, and the second is reaction of this oxide with selenium vapor in nitrogen at atmospheric pressure to form InzSea. Shorter exposure time was needed for complete conversion as the temperature was increased from 400 to 500 "C. Auger depth profiling of the composition of a partially converted film indicated that the conversion process appears to involve three steps: (a) reaction between selenium vapor and the oxide at the surface; (b) subsequent diffusion of selenium into the film until much of the oxide was converted to InSe; (c) further reaction involving selenium vapor and InSe to form InzSe3. It was possible to convert InzSe3 into InSe by reacting it with indium vapor, and it was also possible to incorporate cadmium. p-type InzSe3 and n-type InSe were prepared by this relatively inexpensive process. Resistance and Hall effect measurements gave a variety of resistivity and carrier density values, depending on the preparation conditions. X-ray diffraction indicated that the InzSe3 film may consist of several crystalline phases, and optical absorption spectra indicated a direct bandgap of 1.84 eV. A direct bandgap of 3.64 eV was found for In203, which was n-type and had a very low resistivity and high electron density. IntroductionThere has been a recent interest in the growth of thin