CAPPING LAYERS FOR IMPROVED CRYSTALLIZATION

摘要

Techniques for fabrication of kesterite Cu-Zn-Sn-(Se,S) films and improved photovoltaic devices based on these films are provided. In one aspect, a method of fabricating a kesterite film having a formula Cu2-xZn1+ySn(S1-zSez)4+q, wherein 0=x=1; 0=y=1; 0=z=1; and -1=q=1 is provided which includes the following steps. A substrate is provided. A bulk precursor layer is formed on the substrate comprising Cu, Zn, Sn and at least one of S and Se. A capping layer is formed on the bulk precursor layer comprising at least one of Sn, S and Se. The bulk precursor layer and the capping layer are annealed under conditions sufficient to produce the kesterite film having values of x, y, z and q for any given part of the film that deviate from average values of x, y, z and q throughout the film by less than 20 percent.