Determination of bulk states and interface states distributions in polycrystalline silicon thin‐film transistors

The field‐effect conductance activation energy Ea as a function of the gate voltage Vg is investigated for polycrystalline silicon thin‐film transistors. An analytical expression for Ea is obtained for various models of the bulk and interface states. Using a computer minimization program to fit the experimental Ea vs Vg data with the theory, the energy distribution of the bulk states and the interface states are separated for nonhydrogenated and hydrogenated polycrystalline silicon thin‐film transistors. In both cases, the bulk states have exponential band tails and a wide peak near the midgap and the interface states have an exponential distribution from the band edge.