Improved performance of GaAs-based micro-solar cell with novel polyimide/SiO 2 /TiAu/SiO 2 structure

A novel interconnected structure consisting of a conventional polyimide layer (PM) and an additional SiO 2 /TiAu/SiO 2 sandwich multilayer has been firstly proposed for improving the performance of GaAs micro-solar cell array. The specific experimental investigations on the array with 108 unit cells have demonstrated that the novel structure of PM/SiO 2 /TiAu/SiO 2 can effectively enhance the open-circuit voltage from 75 to 84 V and the fill factor from 35% to 57%. The performance improvement of our devices can be attributed to two aspects. Firstly, the TiAu shielding film can prevent the incident light from penetrating into the GaAs substrate so as to induce the serious substrate leakage current. Secondly, the compact texture of SiO 2 in the novel structure can reduce the perimere recombination due to the crackle or shrinkage of PM. It is indicated that the novel structure can distinctly reduce the leakage current and improve output characteristic of micro-solar cells.