Simultaneous diffusion of Zn and P in InGaAs and GaSb cells for solar and thermophotovoltaic space applications

In_0.53Ga_0.47As (InGaAs) heterostructures and GaSb cells with a pin configuration were developed. These cells can be used as thermophotovoltaic (TPV) converters and as bottom solar cells in high-efficiency tandems with wide gap top cells, respectively. All cells were fabricated by diffusion of Zn and P into undoped layers of InGaAs grown by liquid phase epitaxy (LPE), and into n-GaSb(Te) substrates. The cells had total areas of 1, 0.16, and 0.04 cm². The typical one-sun AM0 25°C efficiency, short-circuit current density, open-circuit voltage, and fill factor, of the InGaAs solar cells were 8.2-9.4%, 45-50.4 mA/cm², 0.35-0.36 V and 0.69-0.71, respectively. The InGaAs TPV devices demonstrated open-circuit voltage voltages in the range of 0.42-0.5 V and short-circuit current densities of 1.5-31 A/cm². The highest fill factor achieved in our cells at 25°C was 0.785 at 15.5 A/cm²