X-ray diffraction study of CdS/CdTe heterostructure for thin-film solar cell: influence of CdS grain size on subsequent growth of (111)-oriented CdTe film

• Published in: Journal of physics. D, Applied physics Vol. 39; no. 8; pp. 1537 - 1542
• Main Authors: Toyama, T, Matsune, K, Oda, H, Ohta, M, Okamoto, H
• Format: Journal Article
• Language: English
• Published: Bristol IOP Publishing 21.04.2006; Institute of Physics
• Subjects: Applied sciences; Energy; Exact sciences and technology; Natural energy; Photovoltaic conversion; Solar cells. Photoelectrochemical cells; Solar energy; Grain size; Crystal orientation; Polycrystal; Interdiffusion; Cadmium sulfide; X ray diffraction; Preferred orientation; Thin film; Photovoltaic cell; Solar cell; Cadmium tellurides; Mismatch lattice; Performance; Figure of merit; Heterostructures
• ISSN: 0022-3727; 1361-6463
• DOI: 10.1088/0022-3727/39/8/013

An extensive x-ray diffraction (XRD) study has been undertaken to examine the influence of two dominant crystallographic orientations of polycrystalline hexagonal CdS films, i.e. (0002) and orientations, on subsequent growths of polycrystalline cubic CdTe films with a (111) preferred orientation because the CdS/CdTe heterostructure plays a crucial role in determining the photovoltaic performance of the CdS/CdTe thin-film solar cells despite a 10% lattice mismatch between CdS and CdTe. XRD measurements for the CdS films fabricated with various fabrication conditions revealed a unique relation between the lattice spacings of (0002) and planes. When the CdS(0002) and/or CdS grain sizes increase, the degree of the (111) preferred orientation of the subsequently grown CdTe, p(111), which is a figure of merit for the highly efficient solar cell, tends to increase, while the lattice spacings of the CdTe(111) plane decreases. Based on these results, the effects of CdS(0002) and CdS grain sizes on p(111) are discussed in conjunction with the decreased CdTe(111) lattice spacings, indicating interdiffusion of S and Te elements at the CdS/CdTe interface, which is effective for reducing the 10% mismatch between CdS and CdTe.