Effect of proton irradiation on electrical properties of CuInSe2 thin films

High-energy proton irradiation (380 keV and 1 MeV) on the electrical properties of CuInSe2 (CIS) thin films has been investigated. The samples were epitaxially grown on GaAs (00 1) substrates by Radio Frequency sputtering. As the proton fluence exceeded 1 x 10(13) cm(-2), the carrier concentration and mobility of the CIS thin films were decreased. The carrier removal rate with proton fluence was estimated to be about 1000 cm(-1). The electrical properties of CIS thin films before and after irradiation were studied between 80 and 300 K. From the temperature dependence of the carrier concentration in CIS thin films, we found N-D = 9.5 x 10(16) cm(-3), N-A = 3.7 x 10(16) cm(-3) and E-D = 21 meV from the fitting to the experimental data on the basis of the charge balance equation. After irradiation, a defect level was created, and N-T = 1 x 10(17) cm(-3) for a fluence of 3 x 10(13) cm(-2), N-T = 5.7 x 10(17) cm(-3) for a fluence of 1 x 10(14) cm(-2) and ET = 95 meV were also obtained from the same fitting. The new defect, which acted as an electron trap, was due to proton irradiation, and the defect density was increased with proton fluence. (C) 2002 Elsevier Science B.V. All rights reserved.