Measurement of interface defect states at oxidized silicon surfaces by constant-capacitance DLTS

Abstract

The interface-state distribution for the as-oxidized surface on single-crystal silicon is dominated by a broad peak centered ∠0.3 eV above the Si valence-band maximum. Theoretical studies by Laughlin, Joannopoulos, and Chadi suggest that this peak is due to a trivalent silicon defect at the Si–SiO2 interface. Constant-capacitance DLTS and the quasistatic capacitance–voltage technique were used to characterize this defect on (100) - and (111) -oriented silicon surfaces. It is shown here that: (1) the characteristic defect is present at the Si–SiO2 interface on both n-type and p-type silicon, (2) the density of the defect is higher on (111) -oriented than on (100) -oriented silicon for identically prepared specimens, and (3) the defect density can be reduced by a high-temperature, postoxidation anneal in either an argon or nitrogen ambient.