Microstructure of Cu(In,Ga)Se-2 films deposited in low Se vapor pressure

The microstructure of Cu(In,Ga)Se-2 (CIGS) films deposited under low Se flu x was studied using scanning electron microscopy, scanning Auger electron s pectroscopy and high resolution and analytical electron microscopy CIGS fil ms were deposited on Mo coated soda-lime glass substrate using the "3-stage " process in which the Se flux used during the third stage was;restricted t o a forth of standard value. In the as-grown CIGS films, voids were; observ ed along the grain boundaries and a Cu2Se phase was identified at the surfa ce and the grain boundaries. The voids and Cu2Se layer were produced by vap orization of an In-Se compound from the films during the third stage of dep osition. A reaction model on the CIGS grain surface is proposed based on th e microstructure observations.