surface of BP nanosheets and inevitably limit the utilization of their intrinsic properties in applications.In addition, scalable synthesis of high-quality bulk BP with high effi ciency is also challenging, although it is the prerequisite for large-scale production of BP nanosheets. Several methods have been developed for the production of bulk BP, including heating white phosphorus under high pressure, [ 17 ] transforming white phosphorus in mercury [ 18 ] or liquid bismuth, [ 19 ] and transformation of red phosphorus using highenergy mechanical milling at ambient conditions. [ 13 ] However, these methods either use toxic chemicals or complex apparatuses, or are time-consuming, or only give small BP crystals or BP nanoparticles. Compared to these methods, the recently developed mineralizer-assisted gas-phase transformation method shows a great potential to effi ciently produce large-size BP crystals under simple and safe conditions. [ 20,21 ] Here, we report the synthesis of centimeter-size bulk BP crystals by an effi cient mineralizer-assisted gas-phase transformation method and scalable clean production of few-layer BP nanosheets by exfoliating these BP crystals in water, utilizing the hydrophilic nature of BP. The bulk BP crystals show high purity and high quality, with a mobility of ca. 242 cm 2 V −1 s −1and current on/off ratio of ca. 5000 at room temperature for their few-layer counterparts made by mechanical exfoliation, and can be effi ciently exfoliated in water to yield a few-layer BP nanosheet dispersion with high concentration. The BP nanosheets retain the high quality of the bulk crystals, have very high crystallinity, and are free of impurities and stable enough in water for further processing and applications. As an example, we demonstrate the use of these BP nanosheets for paper-like high-performance fl exible LIB electrodes by combining them with highly conductive graphene sheets, which show a high specifi c capacity of 501 mAh g −1 , excellent rate capability, and prolonged cycling performance at a current density of 500 mA g −1 .The Experimental Section gives details of the synthesis of large-size high-quality BP crystals using the mineralizerassisted gas-phase transformation method. Figure 1 a shows a 3 mm-sized BP crystal, and BP crystals as large as 6 mm can also be obtained ( Figure S1, Supporting Information). Energy dispersive X-ray spectroscopy (EDS) measurements show that the sample is composed of only P element without any other elements being observed ( Figure S2, Supporting Information). Atomic absorption spectroscopy (AAS) and inductively coupled plasma atomic emission spectrometry (ICP-AES) measurements further indicate that the purity of the BP crystal is higher than 99.8 at%, and therefore it can be directly used without purifi cation. X-ray diffraction (XRD) measurements Atomically thin black phosphorus (BP) has recently attracted a great deal of interest because of its unique electronic and optical properties and a wide range of promising applications. It has a tunable direct ...

Hall elements were fabricated based on high quality chemical vapor deposition grown graphene, and their performance limit was explored. The as-fabricated graphene Hall element exhibits current-related sensitivity of up to 2093 V/AT under 200 μA, and magnetic resolution of around 1 mG/Hz0.5 at 3 kHz. This ultrahigh sensitivity and resolution stem from high carrier mobility, small Dirac point voltage of 3 V, and low carrier density of about 3 × 1011 cm−2 in graphene device. The current sensitivity is found to decrease with increasing current bias at large bias, and this phenomenon is attributed to the drain induced Dirac point shift effect in graphene channel.

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In this study, we correlated the angular dependence of the Raman response of black phosphorus to its crystallographic orientation by using transmission electron microscopy and Raman spectroscopy. It was found that the intensity of the 2 mode reached a maximum when the polarization direction of the incident light was parallel to the zigzag crystallographic orientation. Notably, it was further confirmed that the zigzag crystallographic direction exhibited superior conductance and carrier mobility. Because of the lattice extension along the armchair direction, an intensification of the anisotropic Raman response was observed. This work provides direct evidence of the correlation between anisotropic properties and crystallographic direction and represents a turning point in the discussion of the angular-dependent electronic properties of black phosphorus.♯ These authors contributed equally to this work

Graphene/silicon CMOS hybrid integrated circuits (ICs) should provide powerful functions which combines the ultra-high carrier mobility of graphene and the sophisticated functions of silicon CMOS ICs. But it is difficult to integrate these two kinds of heterogeneous devices on a single chip. In this work a low temperature process is developed for integrating graphene devices onto silicon CMOS ICs for the first time, and a high performance graphene/CMOS hybrid Hall IC is demonstrated. Signal amplifying/process ICs are manufactured via commercial 0.18 um silicon CMOS technology, and graphene Hall elements (GHEs) are fabricated on top of the passivation layer of the CMOS chip via a low-temperature micro-fabrication process. The sensitivity of the GHE on CMOS chip is further improved by integrating the GHE with the CMOS amplifier on the Si chip. This work not only paves the way to fabricate graphene/Si CMOS Hall ICs with much higher performance than that of conventional Hall ICs, but also provides a general method for scalable integration of graphene devices with silicon CMOS ICs via a low-temperature process.

Chemical vapor deposition (CVD) is considered the most promising method for pushing graphene into commercial products. However, CVD grown graphene is usually of low quality. In this work we explore how good can CVD-derived monolayer graphene be. Through the combinational optimization of the main processes of growth, transfer, device fabrication and measurements, we show that the optimized CVD graphene can present performance comparable to mechanical exfoliated ones: in particular, high carrier mobility at room temperature on the Si/SiO2 substrate, perfect electron-hole symmetry and excellent uniformity (the mobility ranged from 5000 to 12,000 cm(2) V(-1) s(-1) with an average mobility of ∼ 8800 cm(2) V(-1) s(-1) and 50% were higher than 10,000 cm(2) V(-1) s(-1)). In addition we found that the adsorbed oxygen and water molecules on graphene lead to p-type doping in graphene, and transferred charges bring charged impurity scattering to the transporting carriers in the graphene channel. It is therefore necessary to carry out electrical measurements under vacuum to obtain high intrinsic carrier mobility CVD grown graphene.

Multifunctional graphene magnetic/hydrogen sensors are constructed for the first time through a simple microfabrication process. The as-fabricated graphene sensor may act as excellent Hall magnetic detector, demonstrating small linearity error within 2% and high magnetic resolution up to 7 mG/Hz(0.5). Meanwhile the same graphene sensor is also demonstrated as high-performance hydrogen sensor with high gas response, excellent linearity, and great repeatability and selectivity. In particular, the graphene sensor exhibits high hydrogen response up to 32.5% when exposed to 1000 ppm hydrogen, outperforming most graphene-based hydrogen sensors. In addition the hydrogen-sensing mechanism of Pd-decorated graphene is systematically explored through investigating its transfer characteristics during gas detection. Our work demonstrates that graphene is a terrific material for multifunctional sensing, which may in principle reduce the complexity of manufacturing process, lower the number of sensors required in the sensing systems, and potentially derive new and more powerful functions.

Transistors were fabricated based on mechanical exfoliated few layer black phosphorus (BP) flakes, and performance change of these devices exposed to air was explored systematically. BP devices were found to suffer severe performance degradation in ambient conditions, and the field effect mobility drops to less than 1/10 of the original in no more than 120 hours after fabrication. However the current on/off ratio shows completely different time dependent behavior to the published result, i.e. increases with exposure time in air, since the minimum current decreases with exposure time to air, which is probably originated from the decrease of layer number in BP. A model is developed to estimate the bandgap change of BP according to the time dependent minimum current of the BP device.