Combining of Anodic Oxidization With Zn-Ga Diffusion to Fabricate High-Efficiency GaSb Thermophotovoltaic Cells

A double Zn-Ga alloy diffusion process combined with precise anodic oxidation was developed to fabricate high-efficiency gallium antimonide (GaSb) thermophotovoltaic (TPV) cells. This method involves comparing different diffusion temperatures to select the most suitable parameters for anodic oxidation, reducing surface recombination, and improving cell efficiency. In traditional double Zn diffusion process for cell fabrication, two Si3N4 layers were deposited on GaSb wafers for diffusion masks and antireflection layers, while mesa etching was used to separate adjacent cells and antireflection layers were formed by anodic oxidation in our experiments. The anodic oxidation layers showed better antireflection ability than sputtered Si3N4 layers, and the cells fabricated by anodic oxidation showed higher output power than those with sputtered Si3N4 layers under the same radiations. Furthermore, we found that an appropriate etching process for the back surface of the cell can reduce series resistance by 52.3% and increase the fill factor (FF) by 0.111, resulting in improved output performance.