Relationship Between Hole Trapping and Interface

We have discovered a general relationship between the distance from the interface at which holes are trapped, and the subsequent generation of interface states. With photon assisted tunneling it has been previously established that there are two types of trapped holes near the Si/SiO₂ interface after high-field stress (Fowler-Nordheim tunneling) and radiation damage. These types are distinguished by their location and behavior upon electron capture. The first type (“near-interfacial trapped holes”) are located between 20 and 70 Å from the interface and completely disappear upon electron capture. The second type (“interfacial trapped holes”) lie within about 15 Å of the interface, and immediately become interface states when they capture an electron. 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.