| Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2014) | |
| Energy Harvesting & Storage | Tuesday Sessions |
| Session EH-TuP |
| Session: | Energy Harvesting & Storage Poster Session |
| Presenter: | JiHyun Choi, Inha University |
| Authors: | J.H. Choi, Inha University S.M. Hwang, Inha University A. Garay Dixon, Inha University C.W. Chung, Inha University |
| Correspondent: | Click to Email |
In photovoltaic solar cell, CdS thin films are mostly used buffer layer due to their wide direct band gap(~2.42 eV). The CdS buffer layers which form a p-n junction with absorber layer are deposited by using a variety of deposition methods such as chemical bath deposition (CBD), spray pyrolysis, vacuum-evaporation and sputtering. Among these techniques, chemical bath deposition is widely used method due to its advantage such as easy and inexpensive process. However, CBD technique also has some disadvantages including production of toxic liquid waste containing Cd and ammonia and difficulty in application to mass production scale. In addition, CBD method should be done in liquid phase, so that it can oxidize the absorber layer.
To overcome these disadvantages of CBD method and to apply for large scale deposition, sputtering of Zn(O,S) thin films was proposed. Sputtering method of Zn(O,S) films can reduce the liquid wastes and save the deposition time for fast deposition. It enables all processes for solar cells to be carried out by vacuum processes without exposure to air. In addition, Zn(O,S) thin films can replace the CdS which contains a toxic Cd. Generally, Zn(O,S) thin films can be deposited by sputtering with pure ZnS target by adding oxygen or by co-sputtering using ZnO and ZnS targets. ZnS itself has very high band gap about 3.6 eV, so that oxygen should be added to control the band gap. Currently, their electrical and optical properties of the sputtered Zn(O,S) films have not been fully studied yet.
In this study, Zn(O,S) thin films are deposited on Cu(In,Ga)Se2 layer and glass substrate by RF sputtering in O2/Ar atmosphere using pure ZnS target. By varying the deposition parameters including O2 concentration in O2/Ar, deposition pressure and RF power, the electrical, optical properties and the morphology of the sputtered Zn(O,S) films were investigated. From this research, the optimal condition for Zn(O,S) buffer layer using sputter method will be obtained.