A Systematic Investigation of Aluminum Oxide Passivating Tunnel Layers for Titanium Oxide Electron-Selective Contacts

摘要

The effects of different processing conditions on aluminum oxide passivating interlayers for silicon/titanium oxide contacts have been investigated. Surface recombination velocity (SRV) and specific contact resistivity are reported as a function of Al2O3 thickness, substrate termination, and thermal treatment. It was observed that Al2O3 passivated most effectively on hydrogen-terminated substrates, achieving an SRV of 20 cm·s^{−1(down from 100 cm·s−1 when wafers were only coated with TiO2) and contact resistivity 0.02 mathrm{Omega}cdot ext{cm}^{2}$. After thermal treatment, however, a contact with a chemical oxide-terminated substrate and without Al2O3 exhibited the lowest recombination with a measured SRV of 40 cm·s−1 and contact resistivity below 0.01 mathrm{Omega}cdot ext{cm}^{2}$. Additionally, only annealed contacts without Al2O3 exhibited ohmic characteristics. The data reported in the present work demonstrate the benefits of certain passivation schemes over others and may aid in the design of future solar cells.}