An implicit analytical surface potential based model for long channel symmetric double-gate MOSFETs accounting for oxide and interface trapped charges

We present analytical models for calculating surface potential for both undoped (intrinsic) and doped (extrinsic) long channel symmetric double-gate MOSFETs. Starting with Poisson's equation, we derive the implicit surface potential equation(s) for the symmetric double-gate MOSFET in the accumulation and depletion/inversion regions of operation. This results in a continuous surface potential curve throughout all operating regions of the device. By introducing a defect potential to surface potential equations for the symmetric double-gate MOSFET, the models add the effects of oxide-trapped charge and interface traps (both uniform and non-uniform distributions) that can build up in the gate dielectric of the device. A drain current model is presented for both the undoped and doped cases of the SDG MOSFET. The accuracy of the surface potential analytical models and drain current models are validated by comparing to numerical results from two dimensional TCAD simulations.