Improvements in electrical properties for the Sn-rich Cu2−xZnSnSe4 bulks with mobility above 50 cm2/V s

Abstract

Effects of the Cu variation in Cu2−xZn0.9Sn1.1Se4 (Sn-rich CZTSe) bulks with x=0–0.3 on the morphological, structural, and electrical properties have been investigated. Conventionally, the rich in Sn is prohibited for CZTSe because of the formation of the n-type and low electrical mobility. Cu2−x(Zn0.9Sn1.1)Se4 pellets show as the p-type at x=0 and 0.1 and the n-type at x=0.2 and 0.3. Sn-rich CZTSe at x=0 and 0.1 has high mobilities of 87.1 and 58.4cm2/Vs and favorable hole concentrations of 7.52×1017 and 4.88×1017cm−3, respectively. SEM surface images have shown that the grains are less densely packed as the copper content decreases. The non-stoichiometric composition of Sn-rich CZTSe under various Cu contents can lead to the intrinsic defects, with which the changes in the structural and electrical properties of the bulks with the Cu ratio can be explained. This work provides the promising results for Sn-rich CZTSe with the Sn excess to control the hole concentration and the Cu content to keep high electrical mobility.