The calculation results of the surface plasmon(SP) energy and Purcell factor of ZnO/NiSi2demonstrate the possibility of using NiSi2to enhance the UV emission of ZnO by SP coupling.Experimentally,ZnO films were deposited on NiSi2layers synthesized by ion implantation,and the roughness of the NiSi2layers spans a large range from 3 to 38 nm,providing favorable conditions for investigating SP-mediated emission.An 11-fold emission enhancement from the ZnO film on the roughest NiSi2layer was obtained,which indicates the possibility that metal silicide layers can be used both as an electrical contact and for emission enhancement.
Polycrystalline silicon（poly-Si） seed layers were fabricated on graphite substrates by magnetron sputtering. It was found that the substrate temperature in the process of magnetron sputtering had an important effect on the crystalline quality,and 700℃was the critical temperature in the formation of Si（220） preferred orientation. When the substrate temperature is higher than 700℃,the peak intensity of X-ray diffraction（XRD） from Si（220） increases distinctly with the increasing of substrate temperature.Moreover,the XRD measurements indicate that the structural property and crystalline quality of poly-Si seed layers are determined by the rapid thermal annealing （RTA） temperatures and time.Specifically,a higher annealing temperature and a longer annealing time could enhance the Si（220） preferred orientation of poly-Si seed layers.
Forward-scattering efficiency （FSE） is first proposed when an Ag nanoparticle serves as the light-trapping structure for thin-film （TF） solar cells because the Ag nanoparticle’s light-trapping efficiency lies on the light-scattering direction of metal nanoparticles.Based on FSE analysis of Ag nanoparticles with radii of 53 and 88 nm,the forward-scattering spectra and light-trapping efficiencies are calculated.The contributions of dipole and quadrupole modes to light-trapping effect are also analyzed quantitatively.When the surface coverage of Ag nanoparticles is 5%,light-trapping efficiencies are 15.5% and 32.3%,respectively,for 53and 88-nm Ag nanoparticles.Results indicate that the plasmon quadrupole mode resonance of Ag nanoparticles could further enhance the light-trapping effect for TF solar cells.
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
