Very low bulk and surface recombination in oxidized silicon wafers

Bulk and surface processes determine the recombination rate in crystalline silicon wafers. In this paper we report effective lifetime measurements for a variety of commercially available float-zone silicon wafers that have been carefully passivated using alnealed silicon oxide. Different substrate resistivities have been explored, including both p-type (boron) and n-type (phosphorus) dopants. Record high effective lifetimes of 29 and 32 ms have been measured for 90 Omega cm n-type and 150 Omega cm p-type silicon wafers, respectively. The dependence of the effective lifetime has been measured for excess carrier densities in the range of 10(12)-10(17) cm(-3) These results demonstrate that very low bulk and surface recombination rates can be maintained during high-temperature oxidation (1050 degreesC) by carefully optimizing the processing conditions.