Low-temperature deposition of high quality β-FeSi2 films by co-sputtering of Fe and Si for β-FeSi2/Si heterojunction solar cell

Single-phase beta-FeSi2 films have been prepared by Fe-Si mixed targets in a facing target sputtering (FTS) system. Compared with depositing iron on silicon, co-sputtering of Fe and Si atoms in as-deposited samples guarantees that Fe and Si atoms only need relative low energy via short distance migration to form iron silicide during the annealing process, which helps decreasing annealing temperature and reducing annealing time. Then pure single-phase beta-FeSi2 films can be obtained at a low annealing temperature 600 degrees C in this instance. By adjusting the sputtering areas of Fe and Si targets, it's convenient to control the Fe/Si atom ratios in as-deposited samples and thus p-type and n-type films can be obtained easily. The best n-type beta-FeSi2 film on Si(111) substrate shows an electron concentration of 1.7x10(16) cm(-3) and a Hall mobility of 488cm(2)/Vs, respectively. An n-beta-FeSi2/p-Si(111) heterojunction solar cell has been fabricated with a conversion efficiency 0.54%. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim