Ultrathin Single-Crystalline CdTe Nanosheets Realized via Van der Waals Epitaxy

5 years ago

Ultrathin Single-Crystalline CdTe Nanosheets Realized via Van der Waals Epitaxy

Zhenxing Wang, Tofik Ahmed Shifa, Yao Wen, Chao Jiang, Jun He, Fengmei Wang, Jie Li, Feng Wang, Lei Yin, Ruiqing Cheng, Kaili Liu

Due to the novel physical properties, high flexibility, and strong compatibility with Si-based electronic techniques, 2D nonlayered structures have become one of the hottest topics. However, the realization of 2D structures from nonlayered crystals is still a critical challenge, which requires breaking the bulk crystal symmetry and guaranteeing the highly anisotropic crystal growth. CdTe owns a typical wurtzite crystal structure, which hinders the 2D anisotropic growth of hexagonal-symmetry CdTe. Here, for the first time, the 2D anisotropic growth of ultrathin nonlayered CdTe as thin as 4.8 nm via an effective van der Waals epitaxy method is demonstrated. The anisotropic ratio exceeds 103. Highly crystalline nanosheets with uniform thickness and large lateral dimensions are obtained. The in situ fabricated ultrathin 2D CdTe photodetector shows ultralow dark current (≈100 fA), as well as high detectivity, stable photoswitching, and fast photoresponse speed (τrising = 18.4 ms, τdecay = 14.7 ms). Besides, benefitting from its 2D planar geometry, CdTe nanosheet exhibits high compatibility with flexible substrates and traditional microfabrication techniques, indicating its significant potential in the applications of flexible electronic and optoelectronic devices. Here, for the first time,the synthesis of large-size ultrathin single-crystalline CdTe nanosheets as thin as 4.8 nm via van der Waals epitaxy is demonstrated. The fabricated ultrathin CdTe photodetector shows not only ultralow dark current, high detectivity, stable photoswitching, and ultrafast photoresponse speed, but also high compatibility with flexible substrates and traditional microfabrication techniques.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/adma.201703122