Modeling strained SiGe buried channel p-MOSFETs: Band-structure and Detailed Quantum Effects

Keywords:
strained SiGe, buried channel MOSFET, current enhancement, six band k.p

Abstract:
We use a Monte Carlo method to investigate hole transport in ultrasmall p-channel MOSFETs with gate lengths of 25 nm. To model band-structure effects like warping, anisotropy and non-parabolicity on carrier transport, our device simulator couples a 2D Poisson solver with a discretized 66 k.p Hamiltonian solver [1] that includes the effect of the confining potential and provides the subband structure in the channel region. To reduce the computational cost, carriers in the source and drain regions are treated as quasi 3D particles unlike previous approaches [2], where they were treated quantum mechanically using appropriate boundary conditions. The band-structure information for carriers in the source/drain regions is included by solving for the eigenenergies of a more compact 66 k.p Hamiltonian. Strain effects in Buried channel strained-SiGe MOSFETs simulation are by employing the 66 Bir-Pikus strain Hamiltonian into the problem. The performance enhancement expected by using strained SiGe devices in place of conventional Si devices is investigated. The SiGe device exhibited an increased transconductance of about 26%. The performance enhancement in terms of drive current enhancement was found to be higher at smaller values of drain voltage corresponding to the low field regime in which mobility enhancement is expected for such structures. At higher gate and drain biases, the performance of the strained SiGe MOSFET with respect to the conventional Si MOSFET degrades.

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Nanotech 2006 Conference Program Abstract