Cry o-Cathodoluminescence Study of Cu 2 ZnSnS 4 Thin Films

Cryo-cathodoluminescence was used to investigate defects present in Cu2ZnSnS4 thin films. Four luminescence peaks of energies P1: 0.90 eV, P2: 1.04 eV, P3: 1.18 eV, and P4: 1.29 eV were investigated in detail and a fifth peak at ~1.6 eV was also noted. Based on a power-series analysis, P1, P2, and P3 are attributed to free-to-bound or donor-acceptor-pair transitions while P4 appears excitonic in nature. This spectral decomposition in energy became more apparent at large current densities. The observed peaks were attributed to specific recombination mechanisms to inform future studies.