Abstract
Transparent conducting metal oxides are being studied and applied intensively in the optoelectronic device industry in recent years. Oxides such as SnO2, ITO, ZnO, CdO etc., are being used in thin solar cell technology, in the fabrication of gas sensor detectors, and in many other applications. ZnO and CdO exhibit complementary properties when analyzed for use as window materials in photovoltaic industry, i.e., ZnO has a wider band gap, but the undoped material is deposited with a significantly higher resistivity than CdO. Moreover, it has been demonstrated that both materials exhibit gas response. Therefore, a mixed (ZnO)X (CdO)1−X oxide might have intermediate properties making it an adequate material for both type of applications. One of the fundamental research lines directed to improve the ratio efficiency/cost in thin films solar cells technology is that related to the use of polycrystalline materials obtained by an inexpensive and suitable for mass production deposition technology. Spray pyrolysis deposition (SPD) technique satisfies to a great extent these requirements. In fact, we are engaged in a systematic study of sprayed CdO and interesting results have been obtained [1–3]. A substantial improvement of the electro-optical properties has been observed after incorporation of fluorine to the spraying solution. Mixed (ZnO)X (CdO)1−X oxide was first obtained by sol-gel technique [4] and more recently it was deposited by SPD [5]. Good crystallinity for phases corresponding to ZnO and CdO was reported to occur simultaneously after thermal treatments at temperatures higher than 400 ◦C. In the present communication we report the results of achieving depositions of mixed (ZnO)X (CdO)1−X oxides by SPD, starting from metal nitrate solutions. For intermediate X -values, peaks corresponding to both, cubic-CdO and hexagonal-ZnO phases are clearly resolved in DRX spectra for as-deposited samples, thus indicating a good crystallinity. Films were deposited on Corning 7059 glass in a SPD installation described elsewhere [1]. Two starting solutions of zinc and cadmium nitrates in distilled water, 0.1 M, were prepared and mixed in different proportions to form the spraying solutions. The studied
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