Li Pengkun, Xiong Tinghui, Wang Lilin, Sun Shujing, Chen Chenlong
College of Chemistry and Materials Science, Fujian Normal University Fuzhou 350007 China.
Key Laboratory of Optoelectronic Materials Chemistry and Physics, Collaborative Innovation Center for Optoelectronic Semiconductors and Efficient Devices, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Science Fuzhou 350002 China
RSC Adv. 2020 Jan 10;10(4):2096-2103. doi: 10.1039/c9ra09689b. eCollection 2020 Jan 8.
The nearly strain-free GaN films were epitaxially grown successfully on the Au-coated -plane sapphire substrate by a convenient chemical vapor deposition approach. The growth of GaN single crystalline epitaxial films is a self-patterned process. The morphology, structure, compositions and optical properties of as-synthesized GaN materials were characterized through field-emission scanning electron microscopy, atomic force microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, energy dispersive spectroscopy mapping, Raman spectroscopy and photoluminescence spectroscopy. The characterization results confirm that the epitaxial GaN films grown on Au-coated -plane sapphire substrates have a single-crystalline and nearly strain-free structure, and exhibit strong UV emission. A possible growth mechanism of the GaN film is proposed: Au-assisted vapor deposition initiates the nucleation of the GaN seeds, and then these seeds grow into inclined inverted hexagonal GaN pyramids with a threefold azimuthal symmetry and vertical inverted hexagonal pyramids; and subsequently, the vertical inverted hexagonal pyramids expand laterally and annihilate the inclined inverted hexagonal pyramids; eventually these vertical pyramids coalesced to form nearly strain-free GaN films. This synthesis strategy provides a new idea for the simple self-patterned growth of nearly strain-free GaN epitaxial films on Au-coated sapphire substrates, and will promote broader applications in GaN-based electronic and optoelectronic devices.
通过一种简便的化学气相沉积方法，在涂有金的-平面蓝宝石衬底上成功外延生长出了几乎无应变的氮化镓薄膜。氮化镓单晶外延薄膜的生长是一个自图案化过程。通过场发射扫描电子显微镜、原子力显微镜、X射线衍射、X射线光电子能谱、能量色散光谱映射、拉曼光谱和光致发光光谱对合成的氮化镓材料的形貌、结构、成分和光学性质进行了表征。表征结果证实，在涂有金的-平面蓝宝石衬底上生长的外延氮化镓薄膜具有单晶且几乎无应变的结构，并表现出强烈的紫外发射。提出了一种氮化镓薄膜可能的生长机制：金辅助气相沉积引发氮化镓籽晶的成核，然后这些籽晶生长成具有三重方位对称性的倾斜倒六方氮化镓金字塔和垂直倒六方金字塔；随后，垂直倒六方金字塔横向扩展并消灭倾斜倒六方金字塔；最终这些垂直金字塔合并形成几乎无应变的氮化镓薄膜。这种合成策略为在涂有金的蓝宝石衬底上简单自图案化生长几乎无应变的氮化镓外延薄膜提供了新思路，并将推动其在基于氮化镓的电子和光电器件中的更广泛应用。
