Method And Apparatus For A Semiconductor Structure

A semiconductor structure, comprising:

• (a) a semiconductor substrate having a front surface and a back surface;
• (b) a first semiconductor layer disposed on the front surface of the semiconductor substrate;
• and
• (c) a second semiconductor layer, disposed on at least a portion of the back surface of the semiconductor substrate, and compositionally graded through its depth with one or more selected dopants.

A solar module, comprising one or more solar cell devices, wherein at least one of the solar cell devices comprises:

• (a) a semiconductor substrate of one conductivity type, having a front surface and a back surface;
• (b) a first semiconductor layer disposed on the front surface of the semiconductor substrate;
• (c) a second semiconductor layer disposed on a portion of the back surface of the semiconductor substrate, wherein the second amorphous semiconductor layer is compositionally graded through its depth with one or more selected dopants, the second semiconductor layer having a selected conductivity type;
• and
• (d) a third semiconductor layer disposed on another portion of the back surface of the semiconductor substrate, and spaced from the second semiconductor layer, wherein the third semiconductor layer is compositionally graded through its depth with one or more selected dopants, the third semiconductor layer having a conductivity type different from that of the second layer.

A method for making a photovoltaic device, comprising:

• (I) forming a first semiconductor layer over a front surface of a semiconductor substrate;
• (II) forming a second semiconductor layer on a portion of a back surface of the semiconductor substrate, by depositing semiconductor material and a dopant over the back surface portion, while altering a concentration of the dopant, so that the second semiconductor layer becomes compositionally-graded through its depth, from substantially intrinsic at the interface with the back surface of the substrate, to substantially conductive at the opposite side;
• and
• (III) forming a third semiconductor layer on another portion of the back surface of the semiconductor substrate, by depositing semiconductor material and a dopant over the back surface portion, while altering a concentration of the dopant, so that the third semiconductor layer becomes compositionally-graded through its depth, from substantially intrinsic at the interface with the back surface of the substrate, to substantially conductive at the opposite side.