Muon spin rotation experiments were performed. It was found that most of the muons were in a diamagnetic environment although, at low temperatures, some 5 to 10% had paramagnetic surroundings. In the case of CuInSe2, the site of the diamagnetic muon was tentatively identified with the antibonding site close to Se. The onset of muon diffusion at the microsecond timescale was observed between 200 and 250K. The pre-exponential factor for the hopping rate and the activation energy were 3.4 x 1010/s and 0.22eV. Trapping occurred above 250K. The diffusion behavior in CuInS2 was similar, but the onset was shifted to higher temperatures by 50K.

Modelling hydrogen in CuInSe2 and CuInS2 solar-cell materials J.M.Gil, P.J.Mendes, L.P.Ferreira, H.V.Alberto, R.C.Vilão, N.Ayres de Campos, A.Weidinger, Y.Tomm, C.Niedermayer, M.V.Yakushev, R.D.Tomlinson, S.P.Cottrell, S.F.J.Cox: Physical Review B, 1999, 59[3], 1912-6