School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ, 85287, USA.
LeRoy Eyring Center for Solid State Science, Arizona State University, Tempe, AZ, 85287, USA.
Nat Commun. 2018 May 15;9(1):1927. doi: 10.1038/s41467-018-04328-z.
Akin to the enormous number of discoveries made through traditional semiconductor alloys, alloying selected 2D semiconductors enables engineering of their electronic structure for a wide range of new applications. 2D alloys have been demonstrated when two components crystallized in the same phase, and their bandgaps displayed predictable monotonic variation. By stabilizing previously unobserved compositions and phases of GaSeTe at nanoscales on GaAs(111), we demonstrate abnormal band bowing effects and phase instability region when components crystallize in different phases. Advanced microscopy and spectroscopy measurements show as tellurium is alloyed into GaSe, nanostructures undergo hexagonal to monoclinic and isotropic to anisotropic transition. There exists an instability region (0.56 < x < 0.67) where both phases compete and coexist, and two different bandgap values can be found at the same composition leading to anomalous band bowing effects. Results highlight unique alloying effects, not existing in single-phase alloys, and phase engineering routes for potential applications in photonic and electronics.
类似于通过传统半导体合金所取得的大量发现，对选定的二维半导体进行合金化可以对其电子结构进行工程设计，从而实现广泛的新应用。当两种成分在同一相中结晶时，已经证明了二维合金的存在，并且它们的能带隙显示出可预测的单调变化。通过在 GaAs(111) 上稳定以前未观察到的 GaSeTe 的成分和纳米尺度的相，可以证明当组件在不同相中结晶时会出现异常的能带弯曲效应和相不稳定区域。先进的显微镜和光谱测量表明，随着碲被合金化到 GaSe 中，纳米结构经历从六方到单斜和各向同性到各向异性的转变。存在一个不稳定区域（0.56 < x < 0.67），其中两个相竞争并共存，并且在相同的组成下可以找到两个不同的带隙值，从而导致异常的能带弯曲效应。研究结果突出了独特的合金化效应，这些效应在单相合金中不存在，并且为光子学和电子学中的潜在应用提供了相工程途径。
