论文标题
在C-Plane Sapphire底物上原子薄的Ga2Se2膜的外延生长
Epitaxial growth of atomically thin Ga2Se2 films on c-plane sapphire substrates
论文作者
论文摘要
扩大二维（2D）材料的种类并改善超薄膜的合成对于半导体行业的发展至关重要。作为最先进的2D材料，GA2SE2在达到原子稀薄的状态时具有有吸引力的光电特性。然而，很少研究其范德华的外延生长，尤其是对于原子上薄膜的生长。在本文中，我们使用分子束外延来合成CA-Plane Sapphire底物上的表面粗糙度降至1.82 nm的GA2SE2单晶膜，通过优化底物温度，SE：GA通量比和生长速率。然后，我们使用3步模式来生长厚度低至3个四边形的厚度和低至0.61 nm的表面粗糙度的GA2SE2膜，远远超过了直接生长的性能。最后，我们发现表面形态在很大程度上取决于SE：GA通量的比率，并且更高的生长速率扩大了适当的通量比率窗口以增长GA2SE2。总体而言，这项工作提高了对蓝宝石底物上过渡后金属单核化物的VDW外延生长机制的理解。
Broadening the variety of two-dimensional (2D) materials and improving the synthesis of ultrathin films are crucial to the development of the semiconductor industry. As a state-of-the-art 2D material, Ga2Se2 has attractive optoelectronic properties when it reaches the atomically-thin regime. However, its van der Waals epitaxial growth, especially for the atomically-thin films, has seldom been studied. In this paper, we used molecular beam epitaxy to synthesize Ga2Se2 single-crystal films with a surface roughness down to 1.82 nm on c-plane sapphire substrates by optimizing substrate temperature, Se:Ga flux ratio, and growth rate. Then we used a 3-step mode to grow Ga2Se2 films with a thickness as low as 3 tetralayers and a surface roughness as low as 0.61 nm, far exceeding the performance of direct growth. Finally, we found that the surface morphology strongly depends on the Se:Ga flux ratio, and higher growth rates widened the suitable flux ratio window for growing Ga2Se2. Overall, this work advances the understanding of the vdW epitaxy growth mechanism for post-transition metal monochalcogenides on sapphire substrates.
