The Role of High-K Dielectrics in Improving the Performance of Metal-Insulator-Semiconductor Solar Cells

This paper assesses the electrical performance of a metal-insulator-semiconductor (MIS) solar cell designed by using different high-k dielectrics. The study is aimed to achieve the optimized device geometrical dimensions while improving the quantum mechanical tunnelling mechanisms. In addition, an overall comparison between the proposed solar cell structures made of crystalline (c-Si) or hydrogenated amorphous (a-Si:H) silicon is presented. In particular, 10-Å-thick HfO2 and Al2O3 layers are used as alternative high-k materials to surmount the conventional SiO2 drawbacks. Besides, in order to achieve the highest possible conversion efficiency (n), we have investigated the oxide physical and geometrical parameters effects on the fundamental cell figure of merits. The obtained results indicate that a MIS solar cell involving HfO2 and a c-Si bulk, with cell thickness of 250 μm and an acceptor doping density of NA = 7 × 1015 cm−3, perform the optimized results, namely JSC = 45.06 mA/cm2,VOC = 0.592 V,FF = 81.95%, and η = 21.85%.At the same time, for an a-Si:H-based thin structure with a cell thickness of 2 μm(NA = 7 × 1015 cm−3) we obtained JSC = 16.3 mA/cm2,VOC = 1.025 V, FF = 78.8%,and η = 13.1%.