Time and light-dependence of electrical passivation of c-Si surfaces with quinhydrone constituent solutions

Quinhydrone has two constituent parts p-benzoquinone and hydroquinone and these components have been dissolved in methanol to passivate hydrogen-terminated silicon surfaces. It has been confirmed that p-benzoquinone is the active component; however, hydroquinone does improve in performance when in contact with the substrates for a longer duration. This effect is independent of substrate doping. The effect of light was also examined. Substrates passivated in full ambient light conditions displayed the highest effective lifetimes. The passivation effect from solutions exposed to light with measurements taken in the dark were compared with that of substrates passivated using a process completely performed in the dark. The passivation effect from these procedures is substrate doping dependent, but not as effective as full light passivation. It is confirmed that the presence of light is facilitating the bonding reaction. The labile proton on methanol is also found to play an important role in passivation. Additionally, protons that help with the effectiveness of passivation process predominantly come from methanol, but not water.