Alberto, H.V.; Vilao, R.C.; Vieira, R.B.L.; Gil, J.M.; Weidinger, A.; Sousa, M.G.; Teixeira, J.P.; da Cunha, A. F.; Leitao, J.P.; Salomé, P.M.P.; Fernandes, P.A.; Törndahl, T.; Proschka, T.; Suter, A.; Salman, Z.: Slow-muon study of quaternary solar-cell materials: Single layers and p-n junctions. Physical Review Materials 2 (2018), p. 025402/1-11
10.1103/PhysRevMaterials.2.025402
Open Access Version
Abstract:
Thin films and p-n junctions for solar cells based on the absorber materials Cu(In,Ga)Se2 and Cu2ZnSnS4 were investigated as a function of depth using implanted low energy muons. The most significant result is a clear decrease of the formation probability of the Mu+ state at the heterojunction interface as well as at the surface of the Cu(In,Ga)Se2 film. This reduction is attributed to a reduced bonding reaction of the muon in the absorber defect layer at its surface. In addition, the activation energies for the conversion from a muon in an atomiclike configuration to a anion-bound position are determined from temperature-dependence measurements. It is concluded that the muon probe provides a measurement of the effective surface defect layer width, both at the heterojunctions and at the films. The CIGS surface defect layer is crucial for solar-cell electrical performance and additional information can be used for further optimizations of the surface.