Ran Sijia, Glen Tom S, Li Bei, Shi Dongliang, Choi In-Suk, Fitzgerald Eugene A, Boles Steven T
Department of Electrical Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR, China.
Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea.
Nano Lett. 2020 May 13;20(5):3492-3498. doi: 10.1021/acs.nanolett.0c00421. Epub 2020 Apr 23.
Speculations regarding electronic and photonic properties of strained germanium (Ge) have perpetually put it into contention for next-generation devices since the start of the information age. Here, the electromechanical coupling of <111> Ge nanowires (NWs) is reported from unstrained conditions to the ultimate tensile strength. Under tensile strain, the conductivity of the NW is enhanced exponentially, reaching an enhancement factor of ∼130 at ∼3.5% of strain. Under strains larger than ∼2.5%, the electrical properties of Ge also exhibit a dependence on the electric field. The conductivity can be further enhanced by ∼2.2× with a high bias condition at ∼3.5% of strain. Cyclic loading tests confirm that the observed electromechanical responses are repeatable, reversible, and related to the changing electronic band structure. These tests reveal the excellent prospects for utilizing strained Ge NWs in photodetector or piezoelectronic transistor applications, but significant challenges remain to realize strict direct band gap devices.
自信息时代开始以来，关于应变锗（Ge）的电子和光子特性的推测一直使其在下一代器件领域备受关注。在此，报道了<111>锗纳米线（NWs）从无应变状态到极限拉伸强度的机电耦合情况。在拉伸应变下，纳米线的电导率呈指数增强，在约3.5%的应变下增强因子达到约130。在大于约2.5%的应变下，锗的电学性质也表现出对电场的依赖性。在约3.5%的应变下，通过高偏置条件，电导率可进一步提高约2.2倍。循环加载测试证实，观察到的机电响应是可重复、可逆的，并且与不断变化的电子能带结构有关。这些测试揭示了在光电探测器或压电晶体管应用中利用应变锗纳米线的良好前景，但要实现严格的直接带隙器件仍面临重大挑战。
