Bingfei Dou

Surface passivation of nano-textured silicon solar cells by atomic layer deposited Al2O3 films

In the work, the surface recombination of silicon nanostructures was investigated. Silicon nanostructures were synthesized using technique of silver catalyzed chemical wet etching, and the passivation layers of SiNx and Al2O3 were deposited on the samples. The thermal atomic layer deposited Al2O3 can conformally cover the rough surface and reduce the defect density of the nanostructures. Moreover, the negative fixed charge in Al2O3 layer introduces the surface field effect passivation. The lifetime measurement result indicates that Al2O3 layers offer much better passivation effect on the silicon nanostructure surface than SiNx layers. The silicon nano-textured solar cells with SiNx and Al2O3 passivation layers were manufactured and measured. The results show that the enhanced solar cell performance was achieved by Al2O3 passivation.

Maskless fabrication of selectively sized silicon nanostructures for solar cell application

A two-step maskless method was used to synthesize silicon nanostructures. In the first step, silver nanoparticles were formed through rapid thermal annealing of silver thin films. The temperature, duration of annealing, and initial thickness of the silver film jointly determined the distribution and diameter of silver particles. In the next step, silicon nanostructures were created using silver catalyzed etching in HF/H2O2. The experiment confirmed that the final sizes of the nanostructures corresponded to the diameters of the silver particles. Further, silicon nanostructure-textured solar cells were manufactured and tested. The surface-reflection ratio of the cells can be decreased to 5% in the 300–1000 nm wavelength range. The current-voltage and quantum efficiency measurements also reveal that silicon nanostructure-textured solar cells exhibit considerable light trapping enhancement. The results also indicate that effective passivation and electrode contact are important for those cells.