Controllable Growth of Vertical Heterostructure GaTexSe1鈥?i>x/Si by Molecular Beam Epitaxy

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• 作者：Shanshan Liu ; Xiang Yuan ; Peng Wang ; Zhi-Gang Chen ; Lei Tang ; Enze Zhang ; Cheng Zhang ; Yanwen Liu ; Weiyi Wang ; Cong Liu ; Chen Chen ; Jin Zou ; Weida Hu ; Faxian Xiu
• 刊名：ACS Nano
• 出版年：2015
• 出版时间：August 25, 2015
• 年：2015
• 卷：9
• 期：8
• 页码：8592-8598
• 全文大小：503K
• ISSN：1936-086X

文摘

Two dimensional (2D) alloys, especially transition metal dichalcogenides, have attracted intense attention owing to their band-gap tunability and potential optoelectrical applications. Here, we report the controllable synthesis of wafer-scale, few-layer GaTe_xSe_1鈥?i>x alloys (0 鈮?x 鈮?1) by molecular beam epitaxy (MBE). We achieve a layer-by-layer growth mode with uniform distribution of Ga, Te, and Se elements across 2 in. wafers. Raman spectroscopy was carried out to explore the composition-dependent vibration frequency of phonons, which matches well with the modified random-element-isodisplacement model. Highly efficient photodiode arrays were also built by depositing few-layer GaTe_0.64Se_0.36 on n-type Si substrates. These p鈥?/i>n junctions have steady rectification characteristics with a rectifying ratio exceeding 300 and a high external quantum efficiency around 50%. We further measured more devices on MBE-grown GaTe_xSe_1鈥?i>x/Si heterostructures across the full range to explore the composition-dependent external quantum efficiency. Our study opens a new avenue for the controllable growth of 2D alloys with wafer-scale homogeneity, which is a prominent challenge in 2D material research.