Analysis and comparison of L valley transport in GaAs, GaSb, and Geultra-thin-body nMOSFETs
Analysis and comparison of L valley transport in GaAs, GaSb, and Geultra-thin-body nMOSFETs
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GaAs、GaSb 和 Ge 超薄体 nMOSFET 中 L 谷输运的分析和比较
DOI：
10.1109/ted.2013.2285394
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发表时间：
2013
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. Alam;S. Takagi;and M. Takenaka
我们通过将体厚度从 5.79 nm 更改为 2.86 nm，系统地分析了 (111) GaAs 超薄体 (UTB) nMOSFET 的 L 谷弹道输运。在 5.79 nm 厚的 GaAs 中，γ-L 能量偏移为 0.2 eV，单个 γ 谷子带主要控制输运。对于 2.86 nm 厚的 GaAs，这种能量偏移减少到 0.054 eV，并且 L 谷输运变得突出。对于 10 nm 栅极、0.5 nm 有效氧化物和 0.6 V VDD，我们观察到片密度提高了一个数量级，通态电流提高了 159%，亚阈值斜率提高了 15%，增强的 L 谷传输使开关延迟提高了 54%。 3 nm (111) GaSb 和 Ge 通道显示出与 2.86 nm GaAs 器件类似的 I-V 特性。亚阈值电流主要是隧道电流，而通态电流是热电流。 GaAs、GaSb 和 Ge MOSFET 的性能与沟道厚度的比较表明，由于增强的 L 谷传输，GaAs 晶体管的通态电流显着改善。我们还将 L 谷设计与类似尺寸的硅 UTB 弹道 nMOSFET 进行了基准测试。
We systematically analyze the L-valley ballistic transport of (111) GaAs ultrathin-body (UTB) nMOSFETs by changing the body thickness from 5.79 to 2.86 nm. The Γ-L energy offset is 0.2 eV in a 5.79-nm-thick GaAs, and the single Γ-valley subband primarily governs the transport. This energy offset reduces to 0.054 eV for a 2.86-nm-thick GaAs, and the L-valley transport becomes prominent. For a 10-nm gate, a 0.5-nm effective oxide, and a 0.6 V VDD, we observe an order of magnitude improvement in the sheet density, a 159% improvement in the on-state current, a 15% improvement in the subthreshold slope, and a 54% improvement in the switching delay from the enhanced L-valley transport. The 3-nm (111) GaSb and Ge channels show the I-V characteristics similar to the 2.86-nm GaAs device. The subthreshold current is primarily tunneling while the on-state current is thermal. Performance comparison of GaAs, GaSb, and Ge MOSFETs against the channel thickness shows a significant improvement of on-state current in the GaAs transistor due to enhanced L-valley transport. We also benchmark the L-valley design against a silicon UTB ballistic nMOSFET of a similar dimension.