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A Study on Ion Exchange Method for Effective Ag Doping of Sputtering-Deposited CdTe Thin Film

스퍼터링 증착한 CdTe 박막의 효과적인 Ag 도핑을 위한 이온 교환법 연구

  • 김철준 (조선대 공대 전기공학과) ;
  • 박주선 (조선대 공대 전기공학과) ;
  • 이우선 (조선대 공대 전기공학과)
  • Received : 2011.04.11
  • Accepted : 2011.05.23
  • Published : 2011.06.01

Abstract

CdTe thin-film solar cell technology is well known that it can theoretically improve its conversion efficiency and manufacturing costs compared to the conventional silicon solar cell technology, due to its optical band gap energy (about 1.45eV) for solar energy absorption, high light absorption capability and low cost requirements for producing solar cells. Although the prior studies obtained the high light absorption, CdTe thin film solar cell has not been come up to the sufficient efficiency yet. So, doping method was selected for the improvement of the electrical characteristics in CdTe solar cells. Some elements including Cu, Ag, Cd and Te were generally used for the p-dopant as substitutional acceptors in CdTe thin film. In this study, the sputtering-deposited CdTe thin film was immersed in $AgNO_3$ solution for ion exchange method to dope Ag ions. The effects of immersion temperature and Ag-concentration were investigated on the optical properties and electrical characteristics of CdTe thin film by using Auger electron spectroscopy depth-profile, UV-visible spectrophotometer, and a Hall effect measurement system. The best optical and electrical characteristics were sucessfully obtained by Ag doping at high temperature and concentration. The larger and more uniform diffusion of Ag ions made increase of the Ag ion density in CdTe thin film to decrease the series resistance as well as mede the faster diffusion of light by the metal ions to enhance the light absorption.

Acknowledgement

Supported by : 한국연구재단

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