Majority carrier surface mobilities in thermally oxidized silicon

A method of evaluation of majority carrier field-effect mobilities in surface space charge regions is described. This method is also adapted for the determination of chargeable (fast) surface state distribution in the gap. Experimental results obtained with both p- and n-type thermally oxidized silicon samples are presented. In these samples, the surface state density was found to be less than 10¹⁰electronic states/cm²and thus were well suited for the evaluation of effective surface mobility by the dc field-effect measurements. The experimental mobilities are compared with those predicted by the theory of Greene et al. It was found that at flatband and at weak surface accumulation, measured values were lower than those theoretically predicted. For the case of strong surface accumulation, the opposite was true.