Growth and properties of silicon filaments for photovoltaic applications

Abstract

Thin silicon filaments were grown from the melt by three different methods: (a) RF-heated float-zone pedestal growth of high-purity, dislocation-free, single-crystal filaments, (b) growth of <112> axis, (111) face, dendrite filaments at high pulling rates from a supercooled melt in a quartz crucible, and (c) capillary die growth of thin-walled, small-diameter Si tube-filaments with high ratio of surface area to volume and concomitant device structure advantages. Minority-carrier lifetime /spl tau/ was used to assess the filaments. For the three growth methods listed above, values as high as 660 /spl mu/sec, 53 /spl mu/sec, and 42 /spl mu/sec were observed, respectively. Thin silicon filaments with good crystallographic perfection, grown at high speeds, may be useful as active semiconductor elements in multiple linear-concentrator-array PV systems and in other optoelectronic applications.