Fig. 5 | Nature Communications

Fig. 5

From: Composition change-driven texturing and doping in solution-processed SnSe thermoelectric thin films

Fig. 5

Compositional engineering of SnSe thin films for hole doping. ac Structural and compositional characterization of SnSe thin films annealed at 400 °C for 1, 5, 9, and 13 min by a, b XRD and c XPS analyses. Vertical lines in a and b indicate the orthorhombic SnSe (blue, JCPDS 32–1382) and the hexagonal SnSe2 phase (red, JCPDS 89–2939), respectively. Regardless of annealing time, all thin films showed XRD patterns that corresponded to the SnSe phase. Particularly, the enlarged XRD patterns in b for 2θ ranging from 13° to 17° show the residual SnSe2 phase in thin films annealed for 1 min at 400 °C. XPS spectra of thin films in the region for 3d5/2 and 3d3/2 of Sn show distinctive peaks at 485.4 and 493.8 eV (purple dotted lines), which are identified as the Sn(2+) oxidation state. Additional peaks at 486.3 and 494.7 eV (orange dotted lines) detected in the 1 min-treated sample can be indexed to the Sn(4+) oxidation state. d Graph shows hole mobilities and hole concentrations of SnSe thin films annealed at 400 °C for 1, 5, 9, and 13 min obtained by Hall effect measurement at room temperature