UV-Ozone Oxide for Surface Clean, Passivation, and Tunneling Contact Applications of Silicon Solar Cells

We demonstrate the versatile use of UV-ozone oxide (UVo) in surface cleaning, surface passivation, diffused junction passivation, and current tunneling applications of crystalline silicon (c-Si) solar cells. A UV-ozone generated oxide is used as a surface clean for random textured c-Si samples and the effective-ness of surface clean is determined by capping with a thin layer of aluminum oxide (AlOx). Our developed UVo clean has resulted in a cleaning efficiency almost comparable to that of the benchmarked RCA clean, yielding a saturation current density of 12 fA/cm(2). When planar and textured c-Si samples are capped by a stack of UVo and AlOx, a UV-ozone growth time of no more than 3 min is found to provide an optimum surface passivation. When tested on phosphorus and boron diffused junctions (with sheet resistance, R-sh of 110-120 omega/?), the UVo and AlOx stack resulted in a J(0) of 11 fA/cm2 or lower. The high-resolution transmission electron microscope imaging revealed that UVo structure is stable upon annealing for passivation activation. Last, when applied as a tunneling contact, the UVo realizes a contact resistivity (rho(c)) of similar to 1 m omega-cm(2) and similar to 20 m omega-cm(2) for boron and phosphorus doped metal-insulator-semiconductor contact structures, respec-tively, with moderately doped diffusions.

Automated summary

We demonstrate the versatile use of UV-ozone oxide (UVo) in various applications of crystalline silicon (c-Si) solar cells, including surface cleaning, passivation, diffused junction passivation, and current tunneling. The UVo clean shows comparable cleaning efficiency to the benchmarked RCA clean. UV-ozone growth time of no more than 3 mins provides optimum surface passivation. The UVo and AlOx stack results in low saturation current density, effective junction passivation, and low contact resistivity for metal-insulator-semiconductor contact structures.