Patent ID: 7901975

Claim:
A method for fabricating a heterojunction photovoltaic device including three p-type absorber layers in contiguous contact, each of the three absorber layers having a different composition and containing cadmium as a principal constituent, the method comprising the steps of: (a) providing an optically transparent substrate coated with a transparent conductive oxide layer thereon; (b) depositing an n-type window layer onto said transparent conductive oxide layer by sputter deposition; (c) depositing a first p-type absorber layer onto said window layer by sputter deposition; (d) depositing a second p-type absorber layer onto said first absorber layer; (e) depositing a third p-type absorber layer onto said second absorber layer by sputter deposition; (f) depositing a CdCl 2 layer onto said third absorber layer; and (g) annealing said CdCl 2 layer and said absorber layers at a temperature in the range of from about 380° C. to about 450° C. to drive the chlorine from said CdCl 2 layer into said absorber layers, thereby forming chlorine doped absorber layers, wherein said second p-type absorber layer is formed of CdTe, said third p-type absorber layer is formed of Cd 1-z Hg z Te, where z ranges from about 0.15 to about 0.20, said substrate is continuously conveyed in steps (b)-(g) without being exposed to atmospheric environment.