Department of Electrical Engineering and Computer Sciences, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
Nano Lett. 2015 Feb 11;15(2):1070-5. doi: 10.1021/nl504029r. Epub 2015 Jan 28.
Room-temperature (RT) ballistic transport of electrons is experimentally observed and theoretically investigated in III-nitrides. This has been largely investigated at low temperatures in low band gap III-V materials due to their high electron mobilities. However, their application to RT ballistic devices is limited by their low optical phonon energies, close to KT at 300 K. In addition, the short electron mean-free-path at RT requires nanoscale devices for which surface effects are a limitation in these materials. We explore the unique properties of wide band-gap III-nitride semiconductors to demonstrate RT ballistic devices. A theoretical model is proposed to corroborate experimentally their optical phonon energy of 92 meV, which is ∼4× larger than in other III-V semiconductors. This allows RT ballistic devices operating at larger voltages and currents. An additional model is described to determine experimentally a characteristic dimension for ballistic transport of 188 nm. Another remarkable property is their short carrier depletion at device sidewalls, down to 13 nm, which allows top-down nanofabrication of very narrow ballistic devices. These results open a wealth of new systems and basic transport studies possible at RT.
室温（RT）弹道电子输运在 III 族氮化物中得到了实验观察和理论研究。由于其电子迁移率高，在低带隙 III-V 材料中已经在低温下对其进行了广泛研究。然而，由于其光学声子能量低，在 300 K 时接近 KT，因此其在 RT 弹道器件中的应用受到限制。此外，RT 时电子平均自由程短，需要纳米级器件，而在这些材料中，表面效应是一个限制。我们探索了宽带隙 III 族氮化物半导体的独特性质，以展示 RT 弹道器件。提出了一个理论模型来证实实验中它们的光学声子能为 92meV，比其他 III-V 半导体大约 4 倍。这允许在更大的电压和电流下运行 RT 弹道器件。还描述了另一个模型，以实验确定弹道输运的特征尺寸为 188nm。另一个显著的特性是其在器件侧壁处的载流子耗尽很短，降至 13nm，这允许自上而下地制造非常窄的弹道器件。这些结果为 RT 提供了大量新的系统和基础传输研究的可能性。
