Diffusion of In and Ga in selenized Cu-In and Cu-Ga precursors

The interdiffusion of Ga and In in a CuGaSe₂/CuInSe₂ thin film diffusion couple and the diffusion of In into CuGaSe₂ thin films were studied by Auger depth profiling. CuGaSe₂ and CuInSe₂ were obtained via selenization by H₂Se of sequentially deposited Cu-Ga and Cu-In layers, respectively. The CuGaSe₂/CuInSe₂ diffusion couple was annealed at 650°C for 30 minutes in an argon atmosphere. The thin film source of In was diffused into CuGaSe₂ in the temperature range of 400°C to 600°C for 30 minutes in an argon atmosphere. Bulk interdiffusion coefficients of In and Ga in the CuGaSe₂/GuInSe₂ couple annealed at 650°C, and the diffusion coefficients of In in CuGaSe₂ films diffusion annealed at various temperatures were determined. The interdiffusion coefficients of In and Ga at 650°C in the diffusion couple are similar (D_In=1.5×10^-11 cm² /sec and D_Ga=4.0×10^-11 cm²/sec). The diffusion coefficients of In in CuGaSe₂ thin films varied from 2.0×10^-13 cm²/sec to 4.5×10^-12 cm²/sec in the temperature range of 400°C to 600°C