Low temperature silicon-based epitaxy for solar cells applications

Epitaxial silicon (Si)-based solar cell technology is an attractive alternative for large-scale and high-throughput manufacturing of cost-effective solar cells through reduced Si consumption. However, due to the optical losses related to reduced Si thickness, it is critical to improve the short-circuit current density (Jsc) of the solar cell. Thus, it becomes imperative to explore a robust scheme to achieve high Jsc for the epitaxial Si solar cells to realize its full potential. The aim of this work is to design, fabricate and characterize epitaxial emitter (epi-emitter) Si solar cells that yield higher Jsc. Three schemes are investigated and compared to determine the most effective scheme to improve the Jsc of the solar cells. Firstly, low temperature Si epitaxy technique is employed to form epi-emitter Si solar cells using bulk crystalline Si substrates, with POCl3 diffused solar cells as the control cell. Next, to lower the contact resistance, the effects of back germanium (Ge) epilayer on an active epitaxial cell performance have been studied; using both highly doped and optimally doped Si substrates. Finally, the effects of architectural and peripheral modifications on the performance of epi-emitter Si solar cells are evaluated. An alternative approach has been demonstrated to grow phosphorus-doped epitaxial Si emitter by ASM 2000 at low temperature (T