Study and optimization of InGaN Schottky solar cell performance

In this work, an extensive numerical simulation of an InxGa1−xN Schottky barrier solar cell is carried out using Silvaco ATLAS simulator. Firstly, the effect of different Schottky metals and Indium fraction (in InxGa1−xN compound) on the solar cell output parameters are studied. A standard Platinum (Pt) work function of 5.65 eV gave a low efficiency of about 7.10% for an Indium (In) molar fraction of 0.54. Since other studies have shown that Pt may have higher work function, this latter was scanned from 5.65 to 6.35 eV. Consequently, the efficiency increased from 7.10% to 22.18% for a work function of 6.35 eV and a 0.7 In fraction. Additional optimizations improved the cell efficiency to 23.3%, by introducing a 4 µm thick intrinsic In0.7Ga0.3N layer between Pt and the doped In0.7Ga0.3N. Further improvement is achieved using a gradual band gap intrinsic layer. Furthermore, this gradual band gap intrinsic layer reduces the effect of interface traps which were found to induce serious degradation of the cell efficiency. The introduction of this gradual band gap intrinsic layer provides a cell efficiency of 38.42% at low trap densities and 28.8% at higher densities.