Fabrication of Silicon-Submicron-Wire-Based Solar Cells on UMG-Si Substrates Using Nickel Catalyst

Abstract

Solar cells based on arrays of vertical Si submicron or nano-sized wires are promising candidates for lowering production-related material costs while still obtaining efficiencies competitive with those of planar multicrystalline Si cells. To the best of our knowledge, our study is the first to examine the growth of silicon submicron wires on upgraded metallurgical-grade Si (UMG-Si) substrates catalyzed by nickel (Ni) using the chemical vapor deposition technique. We examined which conditions are most favorable for the growth of silicon submicron wires by varying the annealing temperature and the annealing time duration: Ni film was annealed with a temperature range of 900–975°C and a time range of 2-12 min. We subsequently analyzed and compared the output characteristics of the silicon submicron-wire-based (Si-SMW-based) solar cells. Our results indicate that silicon wires with diameters ranging from 0.2 to 0.8 μm could be grown with the present technique. Moreover, a conversion efficiency of greater than 1% was achieved for the Si-SMW solar cells fabricated with the Ni catalytic film annealed at 950°C. In particular, annealing the Ni catalytic film for 2 min while growing the submicron wire structure produced a solar cell with an efficiency as high as 2.06%.