Relaxation of light induced metastabilities in Cu(In,Ga)Se2 with different Ga content

Relaxation of the persistent photoconductivity (PPC) in Cu(In,Ga)Se2 has been investigated. Conductance transients have been measured for thin layers in order to analyze carrier trapping and emission processes and compared with capacitance kinetics obtained for a complete solar cell. Relaxation time constants have been recorded as a function of temperature to calculate activation energies of observed processes. Dependence of the relaxation time constant on the light pulse width is also presented both for the layers and a complete solar cell. The origin of the metastability is discussed in terms of a DX-type defect conversion model involving a strong lattice relaxation.