Fabrication of Cu_2SnS_3 films by annealing chemically deposited SnS-CuS precursors in a graphite box

摘要

AbstractMonoclinic$$text {Cu}_{2}text {SnS}_{3}$$Cu2SnS3(CTS) thin films are prepared by annealing chemically deposited SnS–CuS precursors at 520-580$$^{circ }text {C}$$∘Cin a graphite box under atmospheric ($$text {N}_{2}+text {S}_{2}$$N2+S2) pressure, and the effects of annealing temperature and time on the grain growth and morphology of the films are investigated. The films prepared at 520 and 550$$^{circ }{text{C }}$$∘Cshow improvement in grain size and the formation of uniform and compact grains with increasing annealing time. The films prepared at 580$$^{circ }text {C}$$∘Cexhibit good grain growth with grain sizes$$sim 1.0{-}3.0,upmu text {m}$$∼1.0-3.0μm; however, the grain size does not increase with annealing time. Further, annealing time of 120 min at 550 and 580$$^{circ }text {C}$$∘Cleads to material loss. A small amount of$$text {Cu}_{4}text {SnS}_{4}$$Cu4SnS4is detected in the films. In addition, annealing the films at 550 and 580$$^{circ }text {C}$$∘Cfor 90 min with decreased CuS thickness results in a reduction of$$text {Cu}_{4}text {SnS}_{4}$$Cu4SnS4phase, homogeneous grain growth with grain sizes of$$2.0{-}3.5,upmu text {m}$$2.0-3.5μmthroughout the film thickness, and hole mobilities in the range of$$6.0{-}5.3,text {cm}^{2},text {V}^{-1},text {s}^{-1}$$6.0-5.3cm2V-1s-1. These results demonstrate the effectiveness of this annealing approach for producing high quality CTS films with micron-sized grains, which is useful for improving the efficiency of CTS-based thin film solar cells.