Polycrystalline silicon thin film transistors have been widely investigated as active element in liquid crystal flat panel displays. The present work consists of an analysis of experimental transfer characteristics for different active layer and a calculation of the layer resistivity in flat band regime. In order to explain the fall of this parameter in the range of 70 to 90nm, a two-dimensional simulation program is presented. It is based on the resolution of Poisson’s equation.
The results show that the behaviour of this parameter as a function of film thickness can be attributed to several mechanisms, and that its decrease between 70 and 90nm is related to the simultaneous variation of the average carrier concentration and the channel mobility.