Energy state distributions of the Pb centers at the (100), (110), and (111) SiSiO₂ interfaces investigated by Laplace deep level transient spectroscopy

The energy distribution of the Pb centers at the SiSiO₂ interface has been determined using isothermal laplace deep level transient spectroscopy. For the (111) and (110) interface orientations, the distributions are similar and centered at 0.38 eV below the silicon conduction band. This is consistent with only Pb0 states being present. For the (100) orientation, two types of the interface states are observed: one similar to the (111) and (110) orientations while the other has a negative- U character in which the emission rate versus surface potential dependence is qualitatively different from that observed for Pb0 and is presumed to be Pb1.