Photovoltaic effect in Si/SiO2 superlattice microdisk array solar cell structure

Silicon/silicon dioxide (Si/SiO2) superlattice microdisk (SLMD) array solar cell structures were fabricated by a photolithography process. An open-circuit voltage of 661 mV was obtained from a Si/SiO2 SLMD array solar cell using a superlattice composed of 5.6-nm-thick Si layers and 2.5-nm-thick SiO2 layers. This open-circuit voltage is significantly higher than that of polycrystalline silicon microdisk solar cells. We also investigated the quantum efficiency and the temperature dependence of the open-circuit voltage. Detailed analysis suggests that the bandgap of the Si/SiO2 superlattice is approximately 1.4 eV, which is larger than that of c-Si.