DETERMINATION OF BULK STATES AND INTERFACE STATES DISTRIBUTIONS IN POLYCRYSTALLINE SILICON THIN-FILM TRANSISTORS

The field-effect conductance activation energy E(a) as a function of t he gate voltage V(g) is investigated for polycrystalline silicon thin- film transistors. An analytical expression for E(a) is obtained for va rious models of the bulk and interface states. Using a computer minimi zation program to fit the experimental E(a) vs V(g) data with the theo ry, the energy distribution of the bulk states and the interface state s are separated for nonhydrogenated and hydrogenated polycrystalline s ilicon thin-film transistors. In both cases, the bulk states have expo nential band tails and a wide peak near the midgap and the interface s tates have an exponential distribution from the band edge.