Structural, electrical and optical characteristics of CuSbSe2 films prepared by pulsed laser deposition and magnetron sputtering processes

Impurity Phases and Optoelectronic Properties of CuSbSe2 Thin Films Prepared by Cosputtering Process for Absorber Layer in Solar Cells

“…Only two intermetallic compounds, Cu 3 SbSe 3 and Cu 2 Se, were observed under these conditions. These are the typical intermediate phases during the formation of CuSbSe 2 [19] in Cu-rich composition [18], and EDS analysis revealed a Cu:Sb:Se ratio of 36:21:43 in the as-deposited thin film, as shown in Figure 2b. The Cu 3 SbSe 3 impurity phase is known as a p-type semiconductor with a low resistivity, a carrier density in the order of 10 18 cm −3 , and a band gap within the range 1.…”

“…As shown in Figure 1d,e, with an increase in the sputtering power for Sb to 19 and 21 W, the surface showed more pores and larger gaps between particles. Although the Sb content increased at Sb powers of 19 and 21 W and the annealing process was performed at a much lower temperature than the melting point of CuSbSe 2 (480 • C), the CuSbSe 2 could decompose to gaseous Sb 2 Se 3 which could leave gaps and escape from the surface of the thin films [10,19]. The resulting porous and nonuniform surface with the large gaps appears to be unsuitable for the absorption layer in solar cells.…”

“…CuSbSe 2 is still stable but starts to decompose at the sputtering powers of 19 and 21 W, corresponding to Cu-rich, Sb-rich, and Se-poor conditions in the as-deposited thin film, while the phases in the thin films may strongly depend on the growth conditions [10,28]. These gaps seem to lead to the degradation of the optical quality of the thin films, so those conditions are not appropriate for the absorption layer in solar cells [19]. All as-deposited Cu-Sb-Se thin films exhibited an amorphous nature (not shown).…”

“…The inset of Figure 6c shows the mean values of the absorbance over the 380-780 nm (visible) and the 380-1500 nm (visible to NIR) spectral ranges. In the visible spectral region, the mean absorbance of the annealed thin films is 2.36, 2.84, 3.26, 3.04, and 1.73 for Sb sputtering power of 13,15,17,19, and 21 W, respectively. These values decrease to 1.01, 1.58, 1.63, 1.85, and 1.52 for the same powers in the visible to NIR spectral region.…”

“…The importance of rigorous control of the Cu content in thin films for the prevention of phases such as Cu 2 Se and Cu 3 SbSe 3 has been emphasized in many previous reports [5,6,12], when the Sb content is another important factor for the prevention of these secondary phases. Several methods, such as electrodeposition, pulsed laser deposition, sequential evaporation with selenization, spin-coating, and pre-sputtering of Cu with close-spaced sublimation of Sb 2 Se 3 , have been reported to prepare CuSbSe 2 thin films [19]. The magnetron sputtering method offers some merits of superior adhesion of thin films, excellent transfer of composition, uniform surface morphology, straightforward control of deposition rate, low-cost equipment, and possibility for large-area deposition in the full-vacuum operation [20].…”