Radiotracer diffusion of 114mIn in Cu(In,Ga)Se2 thin films

• Diffusion of 114mIn in CIGSe has been investigated (temperature 523 K–723 K).
• Bulk diffusion activation energy of In: (1.42 ± 0.09) eV
• Grain-boundary diffusion activation energy of In: (1.04 ± 0.18)
• Comparison with literature indicates that bulk diffusivity is higher for In than Ga.

Diffusion of 114mIn in polycrystalline Cu(In0.7,Ga0.3)Se2 thin films has been investigated by measuring radiotracer activity depth profiles by means of ion sputtering. The measurements were carried out in the temperature range between 523 K and 723 K. The obtained diffusivities vary between 7.3 × 10− 17 cm2 s− 1 at 523 K and 1.4 × 10− 12cm2 s− 1 at 723 K with an activation energy of (1.42 ± 0.09) eV. The grain boundary diffusivities in this temperature range vary between 1.0 × 10− 12 cm2 s− 1 at 523 K and 2.9 × 10− 8 cm2 s− 1 at 723 K and a first order-of-magnitude estimation of the activation energy for the grain boundary diffusion yields a value of (1.04 ± 0.18) eV.