Scalable synthesis of multilayer h-BN on AlN by metalorganic vapor phase epitaxy: nucleation and growth mechanism
Scalable synthesis of multilayer h-BN on AlN by metalorganic vapor phase epitaxy: nucleation and growth mechanism
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DOI：
10.1088/2053-1583/ab46e6
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发表时间：
2019-10
期刊：
影响因子：
5.5
通讯作者：
Xu Yang;S. Nitta;M. Pristovsek;Yuhuai Liu;Y. Liao;M. Kushimoto;Y. Honda;H. Amano
中科院分区：
文献类型：
--
作者：
Xu Yang;S. Nitta;M. Pristovsek;Yuhuai Liu;Y. Liao;M. Kushimoto;Y. Honda;H. Amano
我们研究了六方氮化硼（h-BN）的成核和生长的AlN模板上的c面蓝宝石的金属有机气相外延作为生长温度，沉积时间和三乙基硼（TEB）分压的函数。通过原子力显微镜获得了h-BN核的横向生长速率约为25 nm min-1，并且从成核密度的温度依赖性中提取了2.1 eV的成核活化能。大的TEB流速强烈增强h-BN核的形成。在降低的TEB流速下，我们观察到由于TEB解吸而导致的核密度显著降低和成核延迟。通过微调生长参数，单晶多层h-BN成功地形成在AlN表面，通过X射线衍射和透射电子显微镜（TEM）证实。h-BN与AlN的外延关系为[0001]h-BN|| [0 0 0 1]AlN和[1 0 −1 0]h-BN|| [1 1 −2 0]来自TEM和电子背散射衍射测量的AlN。此外，TEM表明，初始的h-BN层是不平行的，并倾向于形成半球形。在这些半圆顶（帽状）上，2D横向生长开始，导致在TEM中观察到取向良好的2D多层膜。因此，表面形貌进一步发展以形成没有褶皱的相对平坦的表面，并且最终在较厚的h-BN层处形成典型的六边形状褶皱表面。特别地，小的h-BN核在其外围具有悬挂键，其可以与衬底相互作用，与AlN形成实际键。因此，尽管多层h-BN的基面通过弱的货车范德华力结合，但对基底的选择是重要的。
We studied the nucleation and growth of hexagonal BN (h-BN) on AlN template on c-plane sapphire by metalorganic vapor phase epitaxy as functions of growth temperature, deposition time, and triethylboron (TEB) partial pressure. A lateral growth rate of about 25 nm min−1 for h-BN nuclei was obtained by atomic force microscopy and a nucleation activation energy of 2.1 eV was extracted from the temperature dependence of the nucleation density. A large TEB flow rate strongly enhances the formation of h-BN nuclei. At a reduced TEB flow rate, we observed a significantly decreased nuclei density and a delay in nucleation due to TEB desorption. By fine tuning the growth parameters, single-crystalline multilayer h-BN was successfully formed on AlN surface, as confirmed by x-ray diffraction and transmission electron microscopy (TEM). The epitaxial relationship between h-BN and AlN was [0 0 0 1]h-BN || [0 0 0 1]AlN and [1 0 −1 0]h-BN || [1 1 −2 0]AlN from TEM and electron backscatter diffraction measurements. In addition, TEM showed that the initial h-BN layers are not parallel and tend to form half-domes. On those half-domes (cap-shaped-like) a 2D lateral growth sets on, resulting in a well-oriented 2D multilayer observed in TEM. Thus, the surface topography further develops to form a relatively flat surface without wrinkles and finally a typical hexagon-like wrinkled surface at thicker h-BN layers. Particularly, the small h-BN nuclei have dangling bonds at their periphery that can interact with the substrate, forming actual bonds with AlN. Hence the choice on the substrate is important, despite the basal planes of multilayer h-BN are bonded by a weak van der Waals force.