Abstract: As the device channel length keeps shrunk from several tens nanometers to a few nanometers,it has been commonly agreed upon that the multi-gate structure (including FinFET) is an effective means for improving the device Ion/Ioff ratio.For many years,the effects of quantum mechanics (QM) on the carrier distribution and transport in MOSFETs have been recognized and studied.When the cross-section of a channel is confined to an order of a few nanometers,a more fundamental issue in solid-state physics arises.That is,the dependence of bandstructure or electronic structure on the geometry of the material can no longer be ignored and has non-negligible effects on device characteristics.In this paper,the efficient calculation of bandstructure in the channel region using the first principles is discussed.The electrical characteristics of devices are obtained through the solution of Schrdinger equation with open boundary conditions,based on the carrier transport parameters (such as effective mass and mobility) from bandstructure calculation.The relationship between carrier mobilities and the crystal orientation is also studied,taking into consideration the stress effects on the bandstructure and scattering mechanisms.

Key words: MOSFET,  bandstructure,  nano-scale,  device simulation