| 학회 | 한국재료학회 |
| 학술대회 | 2013년 가을 (11/06 ~ 11/08, 제주롯데호텔) |
| 권호 | 19권 2호 |
| 발표분야 | A. 전자/반도체 재료(Electronic and Semiconductor Materials) |
| 제목 | Effect of Cd/S Concentration Ratio on Photoconductive Properties of Chemical Bath Deposited CdS Thin Films |
| 초록 | CdS thin films have attracted extensive attention in photosensors and thin film solar cell applications as an n-type window layer due to the appropriate direct bandgap energy (2.4 eV) which can absorb the light in visible spectrum region. CdS thin films have been grown by various techniques such as spray pyrolysis, chemical vapor deposition, sputtering, and chemical bath deposition (CBD), etc. Among these various techniques, CBD was known to be simple, low cost and requires low deposition temperature. As-grown CdS thin film is usually a nonstoichiometric and n-type semiconductor. Generally, CdS thin films have photosensitivity in the order of 10-107 and high photoresistivity (106-109 Ω∙cm). To improve electrical properties, CdS thin film is doped with B, Er, or In, and thermally annealed. However, these processes strongly reduce the photosensitivity due to the conversion of photoconductive CdS film to an n-type conductor. For photovoltaic applications such as solar cell window layer, it is important to be able to synthesize CdS thin films which have low photo sheet resistivity and high photosensitivity, simultaneously. In this study, we report the effect of defects of CdS film on electrical resistance and photosensitive characteristics. The CdS thin films were deposited on SiO2/Si and commercial glass from a chemical bath containing 5 ml of cadmium acetate as the Cd source, 5 ml of triethanolamine which functions as the complexing agent for Cd ions, 5 ml of 30 % aqueous ammonium hydroxide for providing OH- in the solution, and 5 ml of thiourea as the S source. In particular, Cd/S concentration ratio and growth temperature were optimized to make defect levels inside the bandgap of CdS. With increasing Cd/S concentration ratio, the CdS thin film showed lower photo sheet resistance and higher photosensitivity. It is attributed to more effective defects formation. We will further discuss the effects of Cd/S concentration ratio and growth temperature on microstructure, optical, and photoconductive properties. |
| 저자 | Rajesh Gudala1, Vinaya Kumar Arepalli2, 김의태3 |
| 소속 | 1Department of Materials Science and Engineering, 2Chungnam National Univ., 3Daejeon |
| 키워드 | Cd/S; Thin Films; CBD |
