Pressure dependence of thePbcenter at the〈111〉Si/SiO2interface

We report the first measurement of the pressure dependence of the electronic gap states at the Si/Si${\mathrm{O}}_2$ interface that are associated with the paramagnetic defect termed the $P_b$ center. The energy level of this amphoteric defect for the transition from double to single occupancy by holes is found by deep-level transient spectroscopy to shift towards the valence-band edge with increasing pressure. Our results are in agreement with the predictions of a cluster-model calculation in which the $P_b$ center is identified with the dangling orbital of an interfacial threefold-coordinated Si atom.