Ag nanoparticles were fabricated on Si substrates by radio-frequency magnetron sputtering and thermal annealing treatments.It was found that Ag nanoparticles are ellipsoid at low annealing temperature,but the axis ratio decreases with the increase of annealing temperature,and a shape transformation from ellipsoid to sphere occurs when the temperature increases to a critical point.The experimental results showed that the surface plasmon resonances depend greatly on the nanoparticles'shape and size,which is in accordance with the theoretical calculation based on discrete dipole approximation.The results of forward-scattering efficiency(FSE) and light trapping spectrum(LTS) showed that Ag nanoparticles annealed at 400°C could strongly enhance the light harvest than those annealed at 300 and 500°C,and that the LTS peak intensity of the former is 1.7 and 1.5 times stronger than those of the later two samples,respectively.The conclusions obtained in this paper showed that Ag ellipsoid nanoparticles with appropriate size is more favorable for enhancing the light trapping.
BAI YiMingWANG JunYIN ZhiGangCHEN NuoFuZHANG XingWangFU ZhenYAO JianXiLI NingHE HaiYangGULI MiNa
A novel interconnected structure consisting of a conventional polyimide layer(PM) and an additional SiO2/TiAu/SiO2 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/SiO2/TiAu/SiO2 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 SiO2 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.
