Dispersive Hole Transport in SiO2
Abstract
A detailed study is presented on the temperature, field, and thickness dependencies of the transient, radiation-induced hole transport in thin films of amorphous SiO2 employed as the gate oxides of metal-oxide-semiconductor (MOS) structures. The samples used in the investigation are clean, radiation-hardened oxides in which less than 2 percent of the holes generated are permanently trapped and therefore are ideal for basic transport studies. The measurements show that for the entire range of temperature (78 to 293 K), field (1 to 6 MV/cm), and thickness (22 to 99 nm) investigated, the time dispersion of the transport can be adequately described by the continuous-time-random-walk (CTRW) model with a single value of the disorder parameter: alpha = 0.25 + or - 0.03. This is a crucial result which indicates rather strict universality of the hole transport with respect to temperature, field, and thickness in clean amorphous SiO2. Changes in these parameters simply affect the time scale for the transport, but not the shape or overall dispersion of the response curves. The observed universality feature has implications for the microscopic basis of the transport, namely that the hole transport proceeds via hopping between localized trapping sites in the SiO2 film, with the dispersion originating primarily from a broad distribution of intersite transfer integrals. Keywords: Charge transport, Photoconductivity, Amorphous insulators, Radiation effects, Integrated circuits, Metal oxide semiconductor devices, Insulator films, Polaron Hopping, Random walk models, Solid-state materials, Devices.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 01, 1987
- Accession Number
- ADA187077
Entities
People
- F. B. Mclean
- H. E. Boesch Jr.
- James M. Mcgarrity
Organizations
- Harry Diamond Laboratories