Finite element simulations of compositionally graded InGaN solar cells

The solar power conversion efficiency of compositionally graded InxGa1−xN solar cells was simulated using a finite element approach. Incorporating a compositionally graded region on the InGaN side of a p-GaN/n-InxGa1−xN heterojunction removes a barrier for hole transport into GaN and increases the cell efficiency. The design also avoids many of the problems found to date in homojunction cells as no p-type high-In content region is required. Simulations predict 28.9% efficiency for a p-GaN/n-InxGa1−xN/n-In0.5Ga0.5N/p-Si/n-Si tandem structure using realistic material parameters. The thickness and doping concentration of the graded region was found to substantially affect the performance of the cells.