Aix Marseille Univ, CNRS, CINAM, Marseille, France.
Sci Rep. 2017 Sep 6;7(1):10642. doi: 10.1038/s41598-017-10300-6.
Fundamental interest for 2D electron gas (2DEG) systems has been recently renewed with the advent of 2D materials and their potential high-impact applications in optoelectronics. Here, we investigate a 2DEG created by the electron transfer from a Ag adatom gas deposited on a Si(111) [Formula: see text]-Ag surface to an electronic surface state. Using low-energy electron microscopy (LEEM), we measure the Ag adatom gas concentration and the 2DEG-induced charge transfer. We demonstrate a linear dependence of the surface work function change on the Ag adatom gas concentration. A breakdown of the linear relationship is induced by the occurrence of the Ag adatom gas superstructure identified as Si(111) [Formula: see text]-Ag only observed below room temperature. We evidence below room temperature a confinement of the 2DEG on atomic terraces characterised by spatial inhomogeneities of the 2DEG-induced charge transfer along with temporal fluctuations. These variations mirror the Ag adatom gas concentration changes induced by the growth of 3D Ag islands and the occurrence of an Ehrlich-Schwoebel diffusion barrier of 155 ± 10 meV.
二维电子气（2DEG）系统的基本兴趣最近随着二维材料的出现及其在光电领域的潜在高影响力应用而重新焕发活力。在这里，我们研究了由沉积在 Si(111)[Formula: see text]-Ag 表面上的 Ag 原子气向电子表面态的电子转移产生的 2DEG。使用低能电子显微镜 (LEEM)，我们测量了 Ag 原子气浓度和 2DEG 诱导的电荷转移。我们证明了表面功函数变化与 Ag 原子气浓度之间的线性关系。这种线性关系的破坏是由仅在室温以下观察到的 Ag 原子气超结构的出现引起的，Ag 原子气超结构被确定为 Si(111)[Formula: see text]-Ag。我们在室温以下证明了 2DEG 的限制在原子平台上，这表现为 2DEG 诱导的电荷转移的空间不均匀性以及时间波动。这些变化反映了由 3D Ag 岛的生长引起的 Ag 原子气浓度变化以及 Ehrlich-Schwoebel 扩散势垒的出现，该势垒为 155±10meV。
