Department of Electronic and Information Engineering, The Hong Kong Polytechnic University, Hong Kong, China.
Sci Rep. 2016 Nov 29;6:37833. doi: 10.1038/srep37833.
High quality wafer-scale free-standing WS grown by van der Waals rheotaxy (vdWR) using Ni as a texture promoting layer is reported. The microstructure of vdWR grown WS was significantly modified from mixture of crystallites with their c-axes both parallel to (type I) and perpendicular to (type II) the substrate to large type II crystallites. Wafer-scale transfer of vdWR grown WS onto different substrates by an etching-free technique was demonstrated for the first time that utilized the hydrophobic property of WS and hydrophilic property of sapphire. Our results show that vdWR is a reliable technique to obtain type-II textured crystallites in WS, which is the key factor for the wafer-scale etching-free transfer. The transferred films were found to be free of observable wrinkles, cracks, or polymer residues. High quality p-n junctions fabricated by room-temperature transfer of the p-type WS onto an n-type GaN was demonstrated with a small leakage current density of 29.6 μA/cm at -1 V which shows superior performances compared to the directly grown WS/GaN heterojunctions.
本文报道了一种通过范德华流变学（vdWR）使用 Ni 作为织构促进层在高质量晶圆级独立 WS 上生长的方法。vdWR 生长 WS 的微观结构从其 c 轴与基底平行（I 型）和垂直（II 型）的晶粒混合物显著改变为大的 II 型晶粒。首次展示了一种无蚀刻技术将 vdWR 生长的 WS 晶圆级转移到不同基底上，该技术利用了 WS 的疏水性和蓝宝石的亲水性。我们的结果表明，vdWR 是获得 WS 中 II 型织构晶体的可靠技术，这是晶圆级无蚀刻转移的关键因素。转移后的薄膜没有观察到明显的皱纹、裂纹或聚合物残留物。通过室温将 p 型 WS 转移到 n 型 GaN 上，成功制备了高质量的 p-n 结，在 -1 V 时漏电流密度为 29.6 μA/cm，与直接生长的 WS/GaN 异质结相比，表现出优异的性能。
