Tin selenide belongs to group IV-VI chalcogenide. Its electrical, optical, and structural properties are attractive for having both direct and indirect bandgaps, and its potential for being a 2D material. Tin selenide is also a component of Cu₂ZnSn(S,Se)₄ and can be combined with other binary compounds to form absorber materials for photovoltaic applications ¹. In this study, tin selenide thin films (SnSe_x) were grown on gold substrates using electrochemical atomic layer deposition (E-ALD) ². E-ALD works by depositing one component followed by the other, keeping the condition simple at room temperature using a three electrode flow cell. A monolayer (ML) of the compound completes one cycle. This type of deposition process adds control to the compound growth by limiting the amount of deposit to less than a ML per cycle. Potentials for deposition were selected based off of cyclic voltammetry of Sn and Se. The Sn deposition potential was varied to see the effect on the thin films. Raman spectroscopy, scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), and x-ray diffraction (XRD) were used to characterize the composition and structure of the deposits. Results from XRD and Raman suggest that the tin selenide films contain both SnSe and SnSe₂. Particle shapes of the deposit vary as a function of Sn deposition potential. Changing the deposition potential of Sn also alters the ratios of Sn and Se. Future studies will include quantification of the SnSe and SnSe₂ present, as well as optimization of the homogeneity thin films.

References

1. Czerniawski, J. M.; Perdue, B. R.; Stickney, J. L., Potential Pulse Atomic Layer Deposition of Cu2Se. Chem Mater 2016, 28 (2), 583-591.

2. Stickney, J. L.; Villegas, I.; Suggs, D. W.; Gregory, B. W., Electrochemical Atomic Layer Epitaxy (ECALE). Abstr Pap Am Chem S 1991, 201, 289-Coll.