Abstract
In state‐of‐the‐art Si/SiO2 wafers the concentration of paramagnetic interface states (≂1010 cm2) is almost too low to be detected by electron spin resonance (ESR). This letter describes experiments which show that the ESR signal of singly occupied dangling bond defects (so called Pb centers) may be considerably enhanced by optical irradiation in the wavelength region 650–1050 nm. Furthermore, the Pb center resonance may be observed as a change in the photocurrent produced by optical excitation in this region. Such spin‐dependent photoconductivity results from the spin selection rules for electron‐hole recombination at the defect. This observation demonstrates that the Pb center levels in Si/SiO2 wafers act as both recombination centers and interface states.