(Received August 14, 1990; accepted for publication November 5, 1990)
In this paper we present results of two-dimensional numerical simulations of both amorphous silicon and NMOS and PMOS polycrystalline silicon thin-film transistors. Both types of devices are modeled using an effective medium approach whereby the defects and grain boundaries in the material are treated as a spatially uniform density of localized states in the band gap. The field-effect mobility is self-consistently calculated from the appropriate band mobility and using one set of parameters for each material we obtain very good agreement between simulations of both output and transfer characteristics and experimental data. The experimental activation energy of the source-drain current for the polycrystalline devices is also found to be in excellent agreement with the numerical simulations.
KEYWORDS:silicon, polycrystalline, amorphous, thin-film transistor, simulation, density of states