Analysis of the T-Si-dependent subthreshold characteristics in lightly-doped asymmetric double-gate MOSFETs

Abstract

The subthreshold characteristics of double-gate (DG) MOSFETs with various thicknesses of a Si film (T-Si) are analyzed. It is found that, in comparison to the symmetrical DG-MOSFET, the subthreshold characteristics of the lightly-doped asymmetric device have a larger dependence on T-Si, which is due to the linear distribution of the potential in the Si-film region. Further, we derive an analytical equation which can explain these phenomena and verify the accuracy of the analytical equation by comparing them with the device simulation results. Due to these T-Si-sensitive subthreshold characteristics, tight control of T-Si is required for lightly-doped asymmetric DG-MOSFETs to keep a large I-on/O-off ratio.