Solid-Phase Epitaxy Emitter for Silicon Solar Cells

Abstract

This paper presents a new emitter formation method, "solid-phase epitaxy emitter," that involves an applied solid-phase epitaxial growth based on the rapid thermal processing of a-Si:H thin films. We describe the solid-phase epitaxial growth of intrinsic and phosphorous-doped a-Si: H thin films through rapid thermal processing using radio-frequency plasma-enhanced chemical vapor deposition. The phase transition of these films results from heat treatment above 600 degrees C. We examined the defects in the epitaxially grown silicon that formed at the phase interfaces. Phosphorous-doped a-Si: H produced using phosphine gas (PH3, diluted H-2) exhibited a diminished crystallinity compared with intrinsic a-Si: H because of the disturbance of dopant atoms. Based on this formation method, we fabricated a solid-phase epitaxy emitter cell with an efficiency of 16.7%. In addition, this method is expected to be simpler and more cost effective than the conventional method.