Electrical properties of radiation-damaged CuInSe thin films

Yoshida, Akira*; Natsume, Satoshi*; Lee, H.-S.*; Okada, Hiroshi*; Wakahara, Akihiro*; Oshima, Takeshi; Ito, Hisayoshi

CuInSe (CIS)-based thin film solar cells have excellent radiation hardness and are promising in applications in space. However, although CIS thin film is used as an absorption layer in the cell, the details of radiation-induced degradation mechanism are not yet clear. In this report, n-type CIS thin film was fabricated by RF sputtering and was annealed at 823 K together with CuSe film evaporated on the CIS thin film, resulting in p-type CIS thin layer. The electrical properties of p-type CIS thin films were investigated. These films were irradiated with high energy electrons, up to the irradiation fluence 210[1/cm] of electrons accelerated up to 2 MeV. Over 110[1/cm], the resistivity began to increase drastically. The temperature dependence of the resistivity was measured below room temperature down to 20 K. These behaviors are explained by the grain-boundary-dominated transport with the increased barrier energy at the grain boundary.