Strain-Modulated L-Valley Ballistic-Transport in (lll) GaAs Ultrathin-Body nMOSFETs
Strain-Modulated L-Valley Ballistic-Transport in (lll) GaAs Ultrathin-Body nMOSFETs
复制标题
(lll) GaAs 超薄体 nMOSFET 中的应变调制 L 谷弹道输运
DOI：
10.1109/ted.2014.2311840
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
and M. Takenaka
中科院分区：
文献类型：
--
作者：
K. Alain;S. Takagi;and M. Takenaka
通过(111)面取向的量子化L谷的电子输运是解决GaAs态密度瓶颈的一种可能方案。量子化将L山谷分为L山谷对和遥远的L山谷对，L、L和L。L山谷对投射到Γ山谷上方的二维布里渊带中心，其人口增强了驱动流。然而，对于典型的5 nm薄体，Γ-L的能量间隔仍为≈0.17 eV，电子输运主要由Γ谷控制。用sp3s*d5轨道基紧束缚模型分析了压缩双轴应变对5 nm(111)Γ超薄体的能级和有效质量的影响。然后，我们使用有效质量薛定谔方程和从sp3s*d5模型中提取的质量和能带来评估10 nm双栅器件的弹道性能。挤压应变通过减少Γ-L和Γ-L谷的能量偏移量，促进了L谷和偏远的L谷的输运。这导致了电荷密度和驱动电流的显著改善。大于2.5 GPA的压应力使偏远的L峡谷甚至低于L峡谷。在这种应力条件下，偏远的L[1̅11]和L[11̅1]山谷控制着状态的传输。L河谷和偏远的L河谷不同的波函数对称性是应力调制增强L河谷输运背后的物理基础。
Electron transport through the quantized L valley of (111) surface orientation is a possible solution to density-of-states bottleneck of GaAs. Quantization splits the L valley into L[111] valley pair and remote L valley pairs, L[111], L[111], and L[111]. The L[111] valley pair projects to the 2-D Brillouin zone center above the Γ valley and its population enhances the drive current. However, for a typical 5-nm thin body, the Γ-L[111] energy separation is still ≈0.17 eV and the Γ valley primarily governs the electron transport. We analyze the compressive biaxial strain effects on the energy levels and effective masses of Γ, L[111], and remote L valleys of a 5-nm (111) GaAs ultrathin body using a sp3s*d5orbital basis tight binding model. We then evaluate the ballistic performance of a 10-nm double-gate device using an effective mass Schrodinger's equation with the extracted masses and band energies from sp3s*d5model. Compressive strain promotes the L[111] and remote L valleys transport by reducing the Γ-L[111] and Γ-remote L valleys energy offsets. This results in a significant improvement in charge density and drive current. A compressive stress larger than 2.5 GPa brings the remote L valleys even below the L[111] valley. Under this stress condition, the remote L[1̅11] and L[11̅1] valleys govern the ON-state transport. The different wavefunction symmetries of L[111] and remote L valleys are the physics behind the stress modulated enhanced L valley transport.