스퍼터링 공정조건에 따른 CdTe 박막의 표면 균일도 특성

Abstract

CdTe thin-film solar cell technology is theoretically well known that it can improve the conversion efficiency and production costs compared to the conventional silicon solar cell technology, due to its optical band gap energy (about 1.4eV) for solar energy absorption, high light absorption capability and low cost requirements for producing solar cells. For low efficiency of the conventional photovoltaic cells with some problems in the fabrication at large-area, CdTe has been widely researched as the suitable material for the commercialization. In this study, the sputtering method, which can improve the cost-efficiency and mass production of solar cells, was employed to deposit the CdTe thin film on the substrates with the various processing conditions such as vacuum pressure and RF-power. The non-uniformity and surface morphology were analyzed using Ellipsometery and atomic force microscope (AFM) in surface of CdTe thin-films deposited with the various processing conditions. As compare to non-uniformity and surface-morphology in these processes conditions, it was divided into conditions for good result processes and bad one. Considering each average rates of deposition, these selected processes conditions were deposited again and made a comparative study on optical and electrical characteristics. To compare to optical characteristics, we measured absorbance of CdTe thin films and it is measured Hall Effect to compare for electrical characteristics. Through the comparison from these results by studying the efficiency influenced by the uniformity and surface characteristics of CdTe thin film on the electrical and optical properties of CdTe thin-film solar cell, it is to find the relationship between the surface-uniformity and the photovoltaic properties of CdTe thin-film solar cell as well as the optimized process conditions for application of CdTe solar cell’s fabrication of large area using sputtering.