A Comprehensive Theoretical Analysis of Hole Ballistic Velocity in Si, SiGe, and Ge: Effect of Uniaxial Strain, Crystallographic Orientation, Body Thickness, and Gate Architecture

作者：Teherani James T^*

来源：IEEE Transactions on Electron Devices, 2017, 64(8): 3316-3323.

DOI：10.1109/TED.2017.2708691

• Ballistic velocity
• band structure
• body thickness
• crystallographic orientation
• double gate (DG)
• Ge
• germanium
• holes
• mobility
• MOSFET
• Si
• SiGe
• silicon
• single gate (SG)
• strain
• uniaxial

This paper presents a detailed theoretical analysis of the implications of nanoscale device structures on the average hole ballistic velocity calculated from quantum-mechanical strain-dependent 6x6 k . p bandstructure simulations. The simulations show that the crystallographic orientation of the uniaxial strain, channel, and surface affect the average ballistic velocity by modifying the energy-momentum (E - k) dispersion of the subbands (from which the ballistic velocity is calculated). Conversely, the analysis shows that semiconductor-body thickness and gate architecture influence the ballistic velocity by modifying the quantum confinement in the structure, which ultimately affects the relative hole occupation of k-states across different subbands. Key results of the work show that a 5-nm-body thickness yields a 6%-12% increase in the ballistic velocity compared to a 10-nm body. Likewise, a single-gate architecture gives up to an 11% increase over a double gate, but the improvement is dependent on the crystallographic surface orientation. Strained Ge shows a significantly enhanced ballistic velocity relative to strained Si for both {100}- and {110}-surface orientations with a predicted hole ballistic velocity exceeding 2 x 10(7) cm/s at n(s)(v)(+) = 5 x 1012 #/cm(2).

• 出版日期2017-8