Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing, MI, 48824, USA.
Department of Physics and Astronomy, Michigan State University, East Lansing, MI, 48824, USA.
Sci Rep. 2017 Jan 10;7:40542. doi: 10.1038/srep40542.
We report the homoepitaxial growth of a metal halide on single crystals investigated with in situ reflection high-energy electron diffraction (RHEED) and ex situ atomic force microscopy (AFM). Epitaxial growth of NaCl on NaCl (001) is explored as a function of temperature and growth rate which provides the first detailed report of RHEED oscillations for metal halide growth. Layer-by-layer growth is observed at room temperature accompanied by clear RHEED oscillations while the growth mode transitions to an island (3D) mode at low temperature. At higher temperatures (>100 °C), RHEED oscillations and AFM data indicate a transition to a step-flow growth mode. To show the importance of such metal halide growth, green organic light-emitting diodes (OLEDs) are demonstrated using a doped NaCl film with a phosphorescent emitter as the emissive layer. This study demonstrates the ability to perform in situ and non-destructive RHEED monitoring even on insulating substrates and could enable doped single crystals and crystalline substrates for a range of optoelectronic applications.
我们报告了一种同型外延生长的金属卤化物在单晶上的研究，采用了原位反射高能电子衍射（RHEED）和非原位原子力显微镜（AFM）。研究了 NaCl 在 NaCl（001）上的外延生长作为温度和生长速率的函数，这提供了第一个详细的金属卤化物生长 RHEED 振荡报告。在室温下观察到逐层生长，同时伴有清晰的 RHEED 振荡，而在低温下生长模式转变为岛（3D）模式。在较高温度（>100°C）下，RHEED 振荡和 AFM 数据表明向台阶流生长模式的转变。为了展示这种金属卤化物生长的重要性，使用掺杂 NaCl 薄膜作为发射层的磷光发射器展示了绿色有机发光二极管（OLED）。这项研究表明，即使在绝缘衬底上也能够进行原位和非破坏性的 RHEED 监测，这可能为一系列光电应用提供掺杂单晶和晶体衬底。
