Evaluation of electron beam induced current profiles of Cu(In,Ga)Se2 solar cells with different Ga-contents

The measurement of electron beam induced current profiles in junction configuration (JEBIC) is a settled method for several semiconductor devices. We discuss the JEBIC method in the light of the special conditions present in the case of thin film Cu(In,Ga)Se2 solar cells. Our previously published results indicate that the charge state of defects close to or at the Cu(In,Ga)Se2/CdS interface depends on the minority carrier distribution, which changes strongly during a scan of the cross section with an electron beam. The charge distribution influences the electrostatic potential and therewith the collection of minority carriers. Here, we present an evaluation method of JEBIC profiles that accounts for this effect. Monte Carlo simulations of the carrier generation help us to consider in detail the influence of surface recombination. We determine the diffusion length, space charge width, surface- and back contact recombination velocity of Cu(In(1-r),Gar)Se2 devices with different Ga-contents r from JEBIC line scans