Luojun Du
Chinese Academy of Sciences
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Publication
Featured researches published by Luojun Du.
Journal of the American Chemical Society | 2017
Jianqi Zhu; Zhichang Wang; Hua Yu; Na Li; Jing Zhang; Jianling Meng; Mengzhou Liao; Jing Zhao; Xiaobo Lu; Luojun Du; Rong Yang; Dongxia Shi; Ying Jiang; Guangyu Zhang
In this work, we report a facile, clean, controllable and scalable phase engineering technique for monolayer MoS2. We found that weak Ar-plasma bombardment can locally induce 2H→1T phase transition in monolayer MoS2 to form mosaic structures. These 2H→1T phase transitions are stabilized by point defects (single S-vacancies) and the sizes of induced 1T domains are typically a few nanometers, as revealed by scanning tunneling microscopy measurements. On the basis of a selected-area phase patterning process, we fabricated MoS2 FETs inducing 1T phase transition within the metal contact areas, which exhibit substantially improved device performances. Our results open up a new route for phase engineering in monolayer MoS2 and other transition metal dichalcogenide (TMD) materials.
Small | 2017
Hua Yu; Zhengzhong Yang; Luojun Du; Jing Zhang; Jinan Shi; Wei Chen; Peng Chen; Mengzhou Liao; Jing Zhao; Jianling Meng; G.S. Wang; Jianqi Zhu; Rong Yang; Dongxia Shi; Lin Gu; Guangyu Zhang
Control of the precise lattice alignment of monolayer molybdenum disulfide (MoS2 ) on hexagonal boron nitride (h-BN) is important for both fundamental and applied studies of this heterostructure but remains elusive. The growth of precisely aligned MoS2 domains on the basal plane of h-BN by a low-pressure chemical vapor deposition technique is reported. Only relative rotation angles of 0° or 60° between MoS2 and h-BN basal plane are present. Domains with same orientation stitch and form single-crystal, domains with different orientations stitch and from mirror grain boundaries. In this way, the grain boundary is minimized and a continuous film stitched by these two types of domains with only mirror grain boundaries is obtained. This growth strategy is also applicable to other 2D materials growth.
Advanced Materials | 2017
Li Xie; Mengzhou Liao; Shuopei Wang; Hua Yu; Luojun Du; Jian Tang; Jing Zhao; Jing Zhang; Peng Chen; Xiaobo Lu; G.S. Wang; Guibai Xie; Rong Yang; Dongxia Shi; Guangyu Zhang
2D semiconductors are promising channel materials for field-effect transistors (FETs) with potentially strong immunity to short-channel effects (SCEs). In this paper, a grain boundary widening technique is developed to fabricate graphene electrodes for contacting monolayer MoS2 . FETs with channel lengths scaling down to ≈4 nm can be realized reliably. These graphene-contacted ultrashort channel MoS2 FETs exhibit superior performances including the nearly Ohmic contacts and excellent immunity to SCEs. This work provides a facile route toward the fabrication of various 2D material-based devices for ultrascaled electronics.
ACS Nano | 2017
Hua Yu; Mengzhou Liao; Wenjuan Zhao; Guodong Liu; X. J. Zhou; Zheng Wei; Xiaozhi Xu; Kaihui Liu; Zonghai Hu; Ke Deng; Shuyun Zhou; Jinan Shi; Lin Gu; Cheng Shen; Tingting Zhang; Luojun Du; Li Xie; Jianqi Zhu; Wei Chen; Rong Yang; Dongxia Shi; Guangyu Zhang
Large scale epitaxial growth and transfer of monolayer MoS2 has attracted great attention in recent years. Here, we report the wafer-scale epitaxial growth of highly oriented continuous and uniform monolayer MoS2 films on single-crystalline sapphire wafers by chemical vapor deposition (CVD) method. The epitaxial film is of high quality and stitched by many 0°, 60° domains and 60°-domain boundaries. Moreover, such wafer-scale monolayer MoS2 films can be transferred and stacked by a simple stamp-transfer process, and the substrate is reusable for subsequent growth. Our progress would facilitate the scalable fabrication of various electronic, valleytronic, and optoelectronic devices for practical applications.
Small | 2016
Jianling Meng; G.S. Wang; Xiaomin Li; Xiaobo Lu; Jing Zhang; Hua Yu; Wei Chen; Luojun Du; Mengzhou Liao; Jing Zhao; Peng Chen; Jianqi Zhu; Xuedong Bai; Dongxia Shi; Guangyu Zhang
MoS2 nanoscrolls are formed by argon plasma treatment on monolayer MoS2 sheet. The nanoscale scroll formation is attributed to the partial removal of top sulfur layer in MoS2 during the argon plasma treatment process. This convenient, solvent-free, and high-yielding nanoscroll formation technique is also feasible for other 2D transition metal dichalcogenides.
Applied Physics Letters | 2017
Luojun Du; Hua Yu; Mengzhou Liao; Shuopei Wang; Li Xie; Xiaobo Lu; Jianqi Zhu; Na Li; Cheng Shen; Peng Chen; Rong Yang; Dongxia Shi; Guangyu Zhang
Stacking two-dimensional materials into van der Waals heterostructures with distinct interlayer twisting angles opens up new strategies for electronic structure and physical property engineering. Here, we investigate how the interlayer twisting angles affect the photoluminescence (PL) and Raman spectra of the MoS2/graphene heterostructures. Based on a series of heterostructure samples with different interlayer twisting angles, we found that the PL and Raman spectra of the monolayer MoS2 in these heterostructures are strongly twisting angle dependent. When the interlayer twisting angle evolves from 0° to 30°, both the PL intensity and emission energy increase, while the splitting of the E2g Raman mode decreases gradually. The observed phenomena are attributed to the twisting angle dependent interlayer interaction and misorientation-induced lattice strain between MoS2 and graphene.
Nature Communications | 2018
Mengzhou Liao; Ze-Wen Wu; Luojun Du; Tingting Zhang; Zheng Wei; Jianqi Zhu; Hua Yu; Jian Tang; Lin Gu; Yanxia Xing; Rong Yang; Dongxia Shi; Yugui Yao; Guangyu Zhang
Van der Waals heterostructures stacked from different two-dimensional materials offer a unique platform for addressing many fundamental physics and construction of advanced devices. Twist angle between the two individual layers plays a crucial role in tuning the heterostructure properties. Here we report the experimental investigation of the twist angle-dependent conductivities in MoS2/graphene van der Waals heterojunctions. We found that the vertical conductivity of the heterojunction can be tuned by ∼5 times under different twist configurations, and the highest/lowest conductivity occurs at a twist angle of 0°/30°. Density functional theory simulations suggest that this conductivity change originates from the transmission coefficient difference in the heterojunctions with different twist angles. Our work provides a guidance in using the MoS2/graphene heterojunction for electronics, especially on reducing the contact resistance in MoS2 devices as well as other TMDCs devices contacted by graphene.Twisting vertically stacked individual layers of two-dimensional materials can trigger exciting fundamental physics and advanced electronic device applications. Here, the authors report five times enhancement in vertical heterojunction conductivity on rotating MoS2 over graphene.
Chinese Physics B | 2017
Li Xie; Luojun Du; Xiaobo Lu; Rong Yang; Dongxia Shi; Guangyu Zhang
Two-dimensional (2D) Van der Waals heterostructures have aroused extensive concerns in recent years. Their fabrication calls for facile and efficient transfer techniques for achieving well-defined structures. In this work, we report a simple and effective dry transfer method to fabricate 2D heterostructures with a clean interface. Using Propylene Carbonate (PC) films as stamps, we are able to pick up various 2D materials flakes from the substrates and unload them to the receiving substrates at an elevated temperature. Various multilayer heterostructures with ultra-clean interfaces were fabricated by this technique. Furthermore, the 2D materials can be pre-patterned before transfer so as to fabricate desired device structures, demonstrating a facile way to promote the development of 2D heterostructures.
Nanoscale | 2017
Ruina Liu; Baoxin Liao; Xiangdong Guo; Debo Hu; Hai Hu; Luojun Du; Hua Yu; Guangyu Zhang; Xiaoxia Yang; Qing Dai
Crystals | 2016
Luojun Du; Hua Yu; Li Xie; Shuang Wu; Shuopei Wang; Xiaobo Lu; Mengzhou Liao; Jianling Meng; Jing Zhao; Jing Zhang; Jianqi Zhu; Peng Chen; G.S. Wang; Rong Yang; Dongxia Shi; Guangyu Zhang