A study of ternary Cu2SnS3 and Cu3SnS4 thin films prepared by sulfurizing stacked metal precursors

P A Fernandes (1, 2) , P M P Salomé (1) , a F da Cunha (1)

1 Departamento de Fisica [Aveiro]
2 Departamento de Física

Thin film Cu 2 SnS 3 and Cu 3 SnS 4 were grown by sulfurization of dc-magnetron sputtered Sn-Cu metallic precursors in a S 2 atmosphere. Different maximum sulfurization temperatures were tested which allowed the study of the Cu 2 SnS 3 phase changes. For a temperature of 350 ºC the films were constituted by tetragonal (I-42m) Cu 2 SnS 3. The films sulfurized at a maximum temperature of 400 ºC presented a cubic (F-43m) Cu 2 SnS 3 phase. Increasing the temperature up to 520 ºC, the Sn content of the layer lowered and orthorhombic (Pmn21) Cu 3 SnS 4 was formed. The phase identification and structural analysis was performed using X-ray Diffraction (XRD) and Electron Back-Scattered Diffraction (EBSD) analysis. Raman scattering analysis was also performed and the comparison with XRD and EBSD data allowed the assignment of peaks at 336 cm -1 and 351 cm -1 for tetragonal Cu 2 SnS 3, 303 cm -1 and 355 cm -1 for cubic Cu 2 SnS 3, and 318 cm -1, 348 cm -1 and 295 cm -1 for the Cu 3 SnS 4 phase. Compositional analysis was done using Energy Dispersive Spectroscopy (EDS) and Induced Coupled Plasma (ICP) analysis. Scanning Electron Microscopy (SEM) was used to study the morphology of the layers. The transmittance and reflectance measurements permitted the estimation the absorbance and the band gap. These ternary compounds present a high absorbance value close to 10 4 cm -1. The estimated band gap energy was 1.35 eV for tetragonal (I-42m) Cu 2 SnS 3, 0.96 eV for cubic (F-43m) Cu 2 SnS 3 and 1.60 eV for orthorhombic (Pmn21) Cu 3 SnS 4. Hot Point Probe was used for the determination of the semiconductor conductivity type. The results show that all samples are p-type semiconductor. Four Point Probe was used to obtain the resistivity of these samples. The resistivity for tetragonal Cu 2 SnS 3, cubic Cu 2 SnS 3 and orthorhombic (Pmn21) Cu 3 SnS 4 are 4.59×10 -2 Ω⋅cm, 1.26×10 -2 Ω⋅cm, 7.40×10 -4 Ω⋅cm, respectively.

Mots clés: : 64.70.kg; 68.55.-a; 78.20.-e; 78.30.Fs; 78.66.Li; 81.15.Cd

P A Fernandes, P M P Salomé, a F da Cunha. A study of ternary Cu2SnS3 and Cu3SnS4 thin films prepared by sulfurizing stacked metal precursors. Journal of Physics D: Applied Physics, 2010, 43 (21), pp.215403. ⟨10.1088/0022-3727/43/21/215403⟩. ⟨hal-00569616⟩