In-situ resistance measurement during the growth of Cu(In, Ga)Se2 films by multi-source evaporation

A novel in-situ resistance measurement technique is presented and used to monitor the evolution of the resistance of Cu(In, Ga)Se2 films during growth. Both 1-stage and 3-stage evaporation processes are evaluated. The resistance of the film is initially > 10⁴ Ω and decreases to ~100 Ω by the end of the deposition, and during cooling, increases again to ~ 10⁴ Ω. When the bell jar is opened and the samples are exposed to air, the resistance rapidly reduces to ~100 Ω. This decrease in resistances requires air and/or moisture and does not occur when the bell jar is `back-filled´ with N2, O2 or 5% H2 + Ar. Since the resistance is a cross grain measurement and the change is so abrupt, the air exposure most likely affects the grain boundary chemistry.