Copper diffusion in thin In 2S 3 layers investigated by Rutherford backscattering spectroscopy

Copper diffusion in thin In ₂S ₃ layers was investigated by measuring copper concentration profiles with Rutherford Backscattering Spectroscopy (RBS). For this purpose In ₂S ₃ layers (thickness 100 nm) were evaporated on crystalline silicon substrates and Cu was diffused from a CuSCN surface layer at temperatures between 150 and 250°C. The CuSCN source layer was removed in pyridine solution before RBS measurements were performed. Diffusion coefficients of Cu in In ₂S ₃ were obtained by simulating the diffusion process in a one-dimensional model and comparing measured and simulated Cu concentration profiles. The values of the exponential prefactor of the diffusion coefficient and of the activation energy were 9 × 10 ^{- 11} cm ²/s and 0.3 eV, respectively.