Discussion of some "trap signatures" observed by admittance spectroscopy in CdTe thin-film solar cells

Jian V. Li, Steve W. Johnston, Xiaonan Li, David S. Albin, Timothy A. Gessert, Dean H. Levi

研究成果: Article同行評審

27 引文 斯高帕斯(Scopus)

摘要

Considerable ambiguity and controversy exist concerning the defect signatures (H1, H2, and H3) frequently observed in admittance spectroscopy of thin-film CdTe solar cells. We prove that the commonly labeled H1 defects, observed in all devices in this study, are actually due to the freeze-out of the majority carriers in the neutral CdTe absorber. This freeze-out is evident in the temperature dependencies of capacitance, carrier concentration, and depletion region width. Contrary to intuitive expectation, the activation energy of freeze-out is less than, not identical to, that of the conductivity. In some other cases, H2 or H3 are observed and attributed to the back-contact potential barrier, rather than to the carrier emission from the traps. We extract the back-contact barrier height from the activation energy of the saturation current determined from the temperature-dependent current-voltage curves using the back-to-back diode model. The back-contact barrier height agrees well with the H2 or H3 energy determined by admittance spectroscopy. We present a more comprehensive and realistic equivalent circuit that includes the admittances from both the back-contact and the neutral absorber.

原文English
文章編號064501
期刊Journal of Applied Physics
108
發行號6
DOIs
出版狀態Published - 2010 九月 15

All Science Journal Classification (ASJC) codes

  • 物理與天文學 (全部)

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