ALUMINUM-INDUCED AC SURFACE PHOTOVOLTAGES IN N-TYPE SILICON-WAFERS

The AC surface photovoltage (SPV) is observed in n-type silicon (Si) wafers rinsed by an alkaline solution composed of ammonium hydroxide, hydrogen peroxide and water (modified RCA rinse) in a quartz container. The SPV increases in an almost stepwise manner at first and then saturates as the native oxide (SiOx) grows in the clean room ambient. When a small quantity of aluminium (Al) is added to the alkaline solution, the saturated value of the SPV becomes dramatically high. This is possibly because AlSiO in the native oxide acts as a negative charge inducing high surface potential, which contributes to the high SPV, in the n-type Si wafers.