We have discovered a general relationship between the location of trapped holes and the subsequent generation of interface states. It has been previously established with photon-assisted tunneling techniques that there are two types of trapped holes near the Si/SiO2interface. These types are distinguished by their location and behavior upon electron capture. The first type ("near-interfacial trapped holes") are observed after x-ray irradiation at low temperature, and are located between 20Å and 70Å from the interface. These holes completely disappear upon electron capture. The second type ("interfacial trapped holes") are detected after high-field stress (Fowler-Nordheim tunneling) and lie within about 15A of the interface. In contrast to near-interfacial trapped holes, these holes immediately become interface states when they capture electrons. The experiments show that these two types of interface states are not independent, but rather holes are first trapped in the near-interfacial sites, and then are converted to interfacial trapped holes by thermal energy or very high fields.
展开▼
