Emitter-less, back-surface alternating-contact solar cell

An Emitter-less, Back-surface, Alternating Contact (EBAC) solar cell comprising:

• a window layer comprising AlGaAs doped to a first conductivity type, where a doping concentration of the AlGaAs comprising the window layer is greater than 2×(1018) cm−3 and less than 4×(1018) cm−3, and where a depth of the window layer is greater than or equal to 10 nm and less than or equal to 50 nm;
• an absorption layer contacting the window layer where the absorption layer comprises GaAs doped to the first conductivity type, where a doping concentration of the GaAs comprising the absorption layer is greater than 1×(1017) cm−3 and less than 3×(1017) cm−3, and where a depth of the absorption layer is greater than or equal to 500 nm and less than or equal to 2000 nm;
• a BSF-heterojunction layer contacting the absorption layer and separated from the window layer by the absorption layer, where the BSF-heterojunction layer comprises AlGaAs doped to the first conductivity type, where a doping concentration of the BSF-heterojunction layer is greater than 2×(1018) cm−3 and less than 3×(1018) cm−3, and where a depth of the window layer is greater than or equal to 10 nm and less than or equal to 50 nm;
• a BSF-contact layer contacting the BSF-heterojunction layer and separated from the absorption layer by the BSF-heterojunction layer, where the BSF-contact layer comprises GaAs doped to the first conductivity type, where a doping concentration of the GaAs comprising the BSF-contact layer is greater than 8×(1018) cm−3 and less than 1.2×(1019) cm−3, and where a depth of the BSF-heterojunction layer is greater than or equal to 10 nm and less than or equal to 50 nm;
• a first contact coupled to the BSF-contact layer and separated from the BSF-heterojunction layer by the BSF-contact layer;
• a heterojunction layer contacting the absorption layer and separated from the window layer by the absorption layer, and the heterojunction layer displaced from the BSF-heterojunction layer, the BSF-contact layer, and the first contact, where the heterojunction layer comprises AlGaAs doped to a second conductivity type, where a doping concentration of the AlGaAs comprising the heterojunction layer is greater than 2×(1018) cm−3 and less than 4×(1018) cm−3, and where a depth of the heterojunction layer is greater than or equal to 10 nm and less than or equal to 50 nm;
• a contact layer contacting the heterojunction layer and separated from the absorption layer by the heterojunction layer, and the contact layer displaced from the BSF-heterojunction layer, the BSF-contact layer, and the first contact, where the contact layer comprises GaAs doped to the second conductivity type, where a doping concentration of the GaAs comprising the contact layer is greater than 8×(1018) cm−3 and less than 1.2×(1019) cm−3, and where a depth of the contact layer is greater than or equal to 10 nm and less than or equal to 50 nm;
• and
• a second contact coupled to the contact layer and separated from the heterojunction layer by the contact layer.