Triple Junction Solar Cell

A triple junction solar cell comprising:

• a bottom Ge layer comprising:
• a substrate layer of doped p+ Ge of thickness at or about 300 μm with a p+ doping concentration level at or about 3e18 cm−3;
• a first emitter layer of n+ Ge of thickness at or about 0.1 μm with an n+ doping concentration level at or about 3e18 cm−3;
• and
• a first window layer of n+ GaAs of thickness at or about 0.05 μm with an n+ doping concentration level at or about 7e18 cm−3;
• a first tunnel junction layer in contact with said bottom Ge layer comprising:
• a first tunnel base layer of n+ GaAs of thickness at or about 0.015 μm with an n+ doping concentration level at or about 1e19 cm−3;
• and
• a first tunnel emitter layer of p+ GaAs of thickness at or about 0.015 μm with a p+ doping concentration level at or about 8e18 cm−3;
• middle GaAs layer in contact with said first tunnel junction layer comprising:
• a first buffer layer of p+ GaAs of thickness at or about 0.3 μm with a p+ doping concentration level at or about 7e18 cm−3;
• a first BSF layer of p+ InGaP of thickness at or about 0.01 μm with a p+ doping concentration level of 5e19 cm−3;
• a first base layer of p+ GaAs of thickness at or about 3.87 μm with a p+ doping concentration level at or about 1e17 cm−3;
• a second emitter layer of n+ GaAs of thickness at or about 0.01 μm with an n+ doping concentration level at or about 4.64e15 cm−3;
• and
• a second window layer of n+ AlInP of thickness at or about 0.01 μm with an n+ doping concentration level at or about 4.64e17 cm−3;
• a second tunnel junction layer in contact with said middle GaAs layer comprising:
• a second tunnel base layer of n+ InGaP of thickness at or about 0.015 μm with an n+ doping concentration level at or about 1e19 cm−3;
• and
• a second tunnel emitter layer of p+ InGaP of thickness at or about 0.015 μm with a p+ doping concentration level at or about 8e18 cm−3;
• and
• a top InGaP layer in contact with said second tunnel junction layer comprising:
• a second buffer layer of p+ AlInP of thickness at or about 0.03 μm with a p+ doping concentration level at or about 1e18 cm−3;
• a second BSF layer of p+ InGaP of thickness at or about 0.01 μm with a p+ doping concentration level at or about 5e19 cm−3;
• a second base layer of p+ InGaP of thickness at or about 0.63 μm with a p+ doping concentration level at or about 1e17 cm−3;
• a third emitter layer of n+ InGaP of thickness at or about 0.17 μm with an n+ doping concentration level at or about 4.64e17 cm−3;
• and
• a third window layer of n+ AlInP of thickness at or about 0.01 μm with an n+ doping concentration level at or about 5e19 cm−3.

A method for forming a triple junction solar cell comprising:

• forming a bottom Ge layer, wherein forming said bottom Ge layer comprises:
• forming a substrate layer of doped p+ Ge of thickness at or about 300 μm with a p+ doping concentration level at or about 3e18 cm−3;
• forming a first emitter layer of n+ Ge of thickness at or about 0.1 μm with an n+ doping concentration level at or about 3e18 cm−3;
• and
• forming a first window layer of n+ GaAs of thickness at or about 0.05 μm with an n+ doping concentration level at or about 7e18 cm−3;
• a first tunnel junction layer in contact with said bottom Ge layer comprising:
• forming a first tunnel base layer of n+ GaAs of thickness at or about 0.015 μm with an n+ doping concentration level at or about 1e19 cm−3;
• and
• forming a first tunnel emitter layer of p+ GaAs of thickness at or about 0.015 μm with a p+ doping concentration level at or about 8e18 cm−3;
• forming a middle GaAs layer in contact with said first tunnel junction layer comprising:
• forming a first buffer layer of p+ GaAs of thickness at or about 0.3 μm with a p+ doping concentration level at or about 7e18 cm−3;
• forming a first BSF layer of p+ InGaP of thickness at or about 0.01 μm with a p+ doping concentration level at or about 5e19 cm−3;
• forming a first base layer of p+ GaAs of thickness at or about 3.87 μm with a p+ doping concentration level at or about 1e17 cm−3;
• forming a second emitter layer of n+ GaAs of thickness at or about 0.01 μm with an n+ doping concentration level at or about 4.64e15 cm−3;
• and
• forming a second window layer of n+ AlInP of thickness at or about 0.01 μm with an n+ doping concentration level at or about 4.64e17 cm−3;
• forming a second tunnel junction layer in contact with said middle GaAs layer comprising:
• forming a second tunnel base layer of n+ InGaP of thickness at or about 0.015 μm with an n+ doping concentration level at or about 1e19 cm−3;
• and
• forming a second tunnel emitter layer of p+ InGaP of thickness at or about 0.015 μm with a p+ doping concentration level at or about 8e18 cm−3;
• and
• forming a top InGaP layer in contact with said second tunnel junction layer comprising:
• forming a second buffer layer of p+ AlInP of thickness at or about 0.03 μm with a p+ doping concentration level at or about 1e18 cm−3;
• forming a second BSF layer of p+ InGaP of thickness at or about 0.01 μm with a p+ doping concentration level at or about 5e19 cm−3;
• forming a second base layer of p+ InGaP of thickness at or about 0.63 μm with a p+ doping concentration level at or about 1e17 cm−3;
• forming a third emitter layer of n+ InGaP of thickness at or about 0.17 μm with an n+ doping concentration level at or about 4.64e17 cm−3;
• and
• forming a third window layer of n+ AlInP of thickness at or about 0.01 μm with an n+ doping concentration level at or about 5e19 cm−3.