Solid-phase epitaxy emitter for silicon solar cells

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°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 H₂) 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.