Bartmann M G, Sistani M, Glassner S, Salem B, Baron T, Gentile P, Smoliner J, Lugstein A
Institute of Solid State Electronics, Technische Universität Wien, Gußhausstraße 25-25a, A-1040 Vienna, Austria.
Univ. Grenoble Alpes, CNRS, CEA/Leti Minatec, Grenoble INP, LTM, F-38054 Grenoble, France.
Nanotechnology. 2021 Apr 2;32(14):145711. doi: 10.1088/1361-6528/abd0b2.
Group-IV based light sources are one of the missing links towards fully CMOS compatible photonic circuits. Combining both silicon process compatibility and a pseudo-direct band gap, germanium is one of the most viable candidates. To overcome the limitation of the indirect band gap and turning germanium in an efficient light emitting material, the application of strain has been proven as a promising approach. So far the experimental verification of strain induced bandgap modifications were based on optical measurements and restricted to moderate strain levels. In this work, we demonstrate a methodology enabling to apply tunable tensile strain to intrinsic germanium [Formula: see text] nanowires and simultaneously perform in situ optical as well as electrical characterization. Combining I/V measurements and μ-Raman spectroscopy at various strain levels, we determined a decrease of the resistivity by almost three orders of magnitude for strain levels of ∼5%. Thereof, we calculated the strain induced band gap narrowing in remarkable accordance to recently published simulation results for moderate strain levels up to 3.6%. Deviations for ultrahigh strain values are discussed with respect to surface reconfiguration and reduced charge carrier scattering time.
基于IV族的光源是实现完全CMOS兼容光子电路的关键环节之一。锗兼具硅工艺兼容性和准直接带隙，是最具潜力的候选材料之一。为克服间接带隙的限制并将锗转变为高效发光材料，施加应变已被证明是一种很有前景的方法。到目前为止，应变诱导带隙修改的实验验证基于光学测量，且限于中等应变水平。在这项工作中，我们展示了一种方法，能够对本征锗[公式：见原文]纳米线施加可调谐拉伸应变，并同时进行原位光学和电学表征。结合不同应变水平下的I/V测量和μ拉曼光谱，我们确定了在约5%的应变水平下，电阻率降低了近三个数量级。据此，我们计算出的应变诱导带隙变窄与最近发表的高达3.6%的中等应变水平模拟结果显著一致。针对超高应变值的偏差，我们从表面重构和电荷载流子散射时间缩短方面进行了讨论。
