CSG Minimodules Using Electron-Beam Evaporated Silicon

Abstract

A key cost driver for thin film silicon technologies in manufacturing is the plasma enhanced chemical vapour deposition (PECVD) process necessary for the production of hydrogenated amorphous silicon. The crystalline silicon on glass (CSG) technology used by CSG Solar can utilize dehydrogenated amorphous silicon and so offers a unique advantage over other thin film silicon technologies in that a more cost effective evaporation process can be considered. This paper reports developments in the e-beam deposition of silicon for PV applications, with a new record efficiency for a planar e-beam deposited silicon thin film solar cell set at 6.7%. The silicon film was deposited at a remarkable 600 nm/min, 30 times faster than routinely achieved by PECVD. We also report developments in e-beam deposition on textured substrates whereby light trapping resulted in a current exceeding 23 mA/cm2 and a record efficiency of 7.4% for a 12-cell 35-cm2 minimodule. The e-beam deposited base was 1.5 μm thick and light trapping was achieved using a silicon surface texture.