Quan Wenzhi, Lu Yue, Wu Qilong, Cheng Yujin, Hu Jingyi, Zhang Zehui, Wang Jialong, Li Zhenzhu, Wang Lili, Ji Qingqing, Zhang Yanfeng
Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871, People's Republic of China.
School of Materials Science and Engineering, Peking University, Beijing 100871, People's Republic of China.
ACS Nano. 2024 Jul 29. doi: 10.1021/acsnano.4c05858.
Exploring emerging two-dimensional (2D) van der Waals (vdW) semiconducting materials and precisely tuning their electronic properties at the atomic level have long been recognized as crucial issues for developing their high-end electronic and optoelectronic applications. As a III-VI semiconductor, ultrathin layered hexagonal GaTe (-GaTe) remains unexplored in terms of its intrinsic electronic properties and band engineering strategies. Herein, we report the successful synthesis of ultrathin -GaTe layers on a selected graphene/SiC(0001) substrate, via molecular beam epitaxy (MBE). The widely tunable quasiparticle band gaps (∼2.60-1.55 eV), as well as the vdW quantum well states (QWSs) that can be strictly counted by the layer numbers, are well characterized by onsite scanning tunneling microscopy/spectroscopy (STM/STS), and their origins are clearly addressed by density functional theory (DFT) calculations. More intriguingly, distinctive 8|8E and 4|4P (Ga) mirror twin boundaries (MTBs) are identified in the ultrathin -GaTe flakes, which can induce decreased band gaps and prominent p-doping effects. This work should deepen our understanding on the electronic tunability of 2D III-VI semiconductors by thickness control and line defect engineering, which may hold promise for fabricating atomic-scale vertical and lateral homojunctions toward ultrascaled electronics and optoelectronics.
长期以来，探索新兴的二维（2D）范德华（vdW）半导体材料并在原子水平上精确调节其电子特性，一直被认为是开发其高端电子和光电子应用的关键问题。作为一种III-VI族半导体，超薄层状六方GaTe（-GaTe）在其本征电子特性和能带工程策略方面仍未得到充分探索。在此，我们报告了通过分子束外延（MBE）在选定的石墨烯/SiC(0001)衬底上成功合成超薄-GaTe层。通过原位扫描隧道显微镜/光谱（STM/STS）很好地表征了可广泛调节的准粒子带隙（约2.60-1.55 eV）以及可由层数严格计数的vdW量子阱态（QWSs），并且通过密度泛函理论（DFT）计算清楚地阐明了它们的起源。更有趣的是，在超薄-GaTe薄片中识别出了独特的8|8E和4|4P（Ga）镜面对称孪晶界（MTBs），它们可导致带隙减小和显著的p型掺杂效应。这项工作应能加深我们对通过厚度控制和线缺陷工程实现二维III-VI族半导体电子可调性的理解，这可能为制造面向超大规模电子学和光电子学的原子尺度垂直和横向同质结带来希望。
