中国物理B ›› 2022, Vol. 31 ›› Issue (10): 108802-108802.doi: 10.1088/1674-1056/ac6b27

• INTERDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY • 上一篇    下一篇

Development of ZnTe film with high copper doping efficiency for solar cells

Xin-Lu Lin(林新璐)1,2, Wen-Xiong Zhao(赵文雄)1, Qiu-Chen Wu(吴秋晨)1,2, Yu-Feng Zhang(张玉峰)1, Hasitha Mahabaduge3, and Xiang-Xin Liu(刘向鑫)1,2,4,†   

  1. 1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China;
    3. Georgia College and State University, Milledgeville, GA 31061, USA;
    4. Institute of Qilu Zhongke Electrical Advanced Electromagnetic Drive Technology, Jinan 250101, China
  • 收稿日期:2022-03-01 修回日期:2022-04-21 出版日期:2022-10-16 发布日期:2022-09-27
  • 通讯作者: Xiang-Xin Liu E-mail:shinelu@mail.iee.ac.cn
  • 基金资助:
    Project supported by the Research Foundation of Institute of Electrical Engineering, Chinese Academy of Sciences, (Grant No. Y710411CSB), the Lujiaxi International Team Project of Chinese Academy of Sciences (Grant No. GJTD- 2018-05), the Chinese Academy of Sciences President’s International Fellowship Initiative (Grant No. 2020VEC0008), and the Fund from the Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology, Qilu Zhongke.

Development of ZnTe film with high copper doping efficiency for solar cells

Xin-Lu Lin(林新璐)1,2, Wen-Xiong Zhao(赵文雄)1, Qiu-Chen Wu(吴秋晨)1,2, Yu-Feng Zhang(张玉峰)1, Hasitha Mahabaduge3, and Xiang-Xin Liu(刘向鑫)1,2,4,†   

  1. 1. Institute of Electrical Engineering, Chinese Academy of Sciences, Beijing 100190, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China;
    3. Georgia College and State University, Milledgeville, GA 31061, USA;
    4. Institute of Qilu Zhongke Electrical Advanced Electromagnetic Drive Technology, Jinan 250101, China
  • Received:2022-03-01 Revised:2022-04-21 Online:2022-10-16 Published:2022-09-27
  • Contact: Xiang-Xin Liu E-mail:shinelu@mail.iee.ac.cn
  • Supported by:
    Project supported by the Research Foundation of Institute of Electrical Engineering, Chinese Academy of Sciences, (Grant No. Y710411CSB), the Lujiaxi International Team Project of Chinese Academy of Sciences (Grant No. GJTD- 2018-05), the Chinese Academy of Sciences President’s International Fellowship Initiative (Grant No. 2020VEC0008), and the Fund from the Institute of Electrical Engineering and Advanced Electromagnetic Drive Technology, Qilu Zhongke.

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摘要： Since a hole barrier was formed in back contact due to mismatch of work function, the back contact material for CdTe cell has been a significant research direction. The ZnTe:Cu is an ideal back contact material, which reduces the valence band discontinuity and can be used as the electron back reflection layer to inhibit interface recombination. The conductivity of ZnTe:Cu film is improved by applying RF-coupled DC sputtering and post-deposition heat treatment. The doping efficiency is computed as the ratio of free hole density and copper concentration, which can be correlated with performance for CdTe-based solar cell. The higher doping efficiency means that more copper atoms substitute for Zn sites in ZnTe lattices and less mobilized copper atoms remain which can enter into the CdTe absorber layer. Copper atoms are suspected as dominant element for CdTe-based cell degradation. After optimizing the ZnTe:Cu films, a systematic study is carried out to incorporate ZnTe:Cu film into CdTe solar cell. The EQE spectrum is kept relatively stable over the long wavelength range without decreasing. It is proved that the conduction band barrier of device with ZnTe:Cu/Au contact material has an effect on the EQE response, which works as free electron barrier and reduces the recombination rate of free carrier. According to the dark J—V data or the light J—V data in the linear region, the current indicates that the intercept gives the diode reverse saturation current. The results of ideality factor indicate that the dominant recombination occurs in the space charge region. In addition, the space charge density and depletion width of solar cell can be estimated by C—V profiling.

关键词: solar cell, radio frequency sputtering, doping efficiency, post-deposition heat treatment

Abstract: Since a hole barrier was formed in back contact due to mismatch of work function, the back contact material for CdTe cell has been a significant research direction. The ZnTe:Cu is an ideal back contact material, which reduces the valence band discontinuity and can be used as the electron back reflection layer to inhibit interface recombination. The conductivity of ZnTe:Cu film is improved by applying RF-coupled DC sputtering and post-deposition heat treatment. The doping efficiency is computed as the ratio of free hole density and copper concentration, which can be correlated with performance for CdTe-based solar cell. The higher doping efficiency means that more copper atoms substitute for Zn sites in ZnTe lattices and less mobilized copper atoms remain which can enter into the CdTe absorber layer. Copper atoms are suspected as dominant element for CdTe-based cell degradation. After optimizing the ZnTe:Cu films, a systematic study is carried out to incorporate ZnTe:Cu film into CdTe solar cell. The EQE spectrum is kept relatively stable over the long wavelength range without decreasing. It is proved that the conduction band barrier of device with ZnTe:Cu/Au contact material has an effect on the EQE response, which works as free electron barrier and reduces the recombination rate of free carrier. According to the dark J—V data or the light J—V data in the linear region, the current indicates that the intercept gives the diode reverse saturation current. The results of ideality factor indicate that the dominant recombination occurs in the space charge region. In addition, the space charge density and depletion width of solar cell can be estimated by C—V profiling.

Key words: solar cell, radio frequency sputtering, doping efficiency, post-deposition heat treatment

中图分类号:  (Thin film III-V and II-VI based solar cells)

  • 88.40.jm
81.15.Cd (Deposition by sputtering) 88.40.hj (Efficiency and performance of solar cells) 81.20.-n (Methods of materials synthesis and materials processing)