Patent ID: 8288645

Claim:
A method for fabricating a single heterojunction solar cell, the method comprising: providing a first semiconductor substrate lightly doped with a first dopant type, the substrate having a topside, a backside, and a first energy bandgap; forming a second semiconductor overlying a region of the substrate backside, the second semiconductor having a second energy handgap, larger than the first energy handgap; forming a third semiconductor layer overlying the first semiconductor substrate topside, moderately doped with the first dopant; texturing a top surface of the third semiconductor layer; forming a single heterojunction as follows: forming a first electrode element selected from a group consisting of an emitter and a base in the substrate backside, where the emitter is heavily doped with a second dopant type, opposite of the first dopant type, and where the base in heavily doped with the first dopant; forming a second electrode element selected from the group consisting of the base and the emitter in the second semiconductor, wherein the second electrode element consists of the base or emitter unselected in the first electrode; forming a first electrical contact to the emitter; and, forming a second electrical contact to the base.