铜锌锡硫带边电子结构及缺陷态的光学表征

The bandedge electronic structure including the optical bandgap, band-tail states, and deep/ shallow donor and acceptor levels in Cu₂ZnSnS₄ semiconductor was analyzed by absorption, photocurrent and photoluminescence spectroscopy, and the theoretical reports. It is revealed that the Sn_Zn-related defect in Cu₂ZnSnS₄ with abundant defect states is one of the key factors affecting the band-edge electronic structure. High concentration of the neutral defect cluster[2 Cu_Zn + Sn_Zn]can narrow the band gap substantially, while the partially-passivated(ionic)defect cluster[Cu_Zn + Sn_Zn]is the main deep donor defect. A large number of band-tail states are responsible for the obvious red-shift of the bandedge-related photoluminescence transition energy. These detrimental defects related to Sn_Zncan be effectively suppressed by properly reducing the Sn content in the copper-poor and zinc-rich growth condition, which also avoids the narrowing of the optical bandgap of the Cu₂ZnSnS₄ absorption layer.