Laemmle, A., Wuerz, R., Schwarz, T., Cojocaru-Mirédin, O., Choi, P.-P., & Powalla, M. (2014). Investigation of the diffusion behavior of sodium in Cu(In,Ga)Se2 layers. Journal of Applied Physics, 115(15): 154501. doi:10.1063/1.4871457.