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1.
Gui Chen Zhe Liu Bo Liang Gang Yu Zhong Xie Hongtao Huang Bin Liu Xianfu Wang Di Chen Ming‐Qiang Zhu Guozhen Shen 《Advanced functional materials》2013,23(21):2681-2690
Zn3As2 is an important p‐type semiconductor with the merit of high effective mobility. The synthesis of single‐crystalline Zn3As2 nanowires (NWs) via a simple chemical vapor deposition method is reported. High‐performance single Zn3As2 NW field‐effect transistors (FETs) on rigid SiO2/Si substrates and visible‐light photodetectors on rigid and flexible substrates are fabricated and studied. As‐fabricated single‐NW FETs exhibit typical p‐type transistor characteristics with the features of high mobility (305.5 cm2 V?1 s?1) and a high Ion/Ioff ratio (105). Single‐NW photodetectors on SiO2/Si substrate show good sensitivity to visible light. Using the contact printing process, large‐scale ordered Zn3As2 NW arrays are successfully assembled on SiO2/Si substrate to prepare NW thin‐film transistors and photodetectors. The NW‐array photodetectors on rigid SiO2/Si substrate and flexible PET substrate exhibit enhanced optoelectronic performance compared with the single‐NW devices. The results reveal that the p‐type Zn3As2 NWs have important applications in future electronic and optoelectronic devices. 相似文献
2.
Zhou Zhang Lai Mun Wong Hou Xiao Wang Zhi Peng Wei Wei Zhou Shi Jie Wang Tom Wu 《Advanced functional materials》2010,20(15):2511-2518
In‐plane growth of Mg2SiO4 nanowires on Si substrates is achieved by using a vapor transport method with Au nanoparticles as catalyst. The self‐assembly of the as‐grown nanowires shows dependence on the substrate orientation, i.e., they are along one, two, and three particular directions on Si (110), (100), and (111) substrates, respectively. Detailed electron microscopy studies suggest that the Si substrates participate in the formation of Mg2SiO4, and the epitaxial growth of the nanowires is confined along the Si <110> directions. This synthesis route is quite reliable, and the dimensions of the Mg2SiO4 nanowires can be well controlled by the experiment parameters. Furthermore, using these nanowires, a lithography‐free method is demonstrated to fabricate nanowalls on Si substrates by controlled chemical etching. The Au nanoparticle catalyzed in‐plane epitaxial growth of the Mg2SiO4 nanowires hinges on the intimate interactions between substrates, nanoparticles, and nanowires, and our study may help to advance the developments of novel nanomaterials and functional nanodevices. 相似文献
3.
T.‐S. Yoon J. Oh S.‐H. Park V. Kim B.G. Jung S.‐H. Min J. Park T. Hyeon K.‐B. Kim 《Advanced functional materials》2004,14(11):1062-1068
The adsorption behavior of colloidal maghemite (γ‐Fe2O3) nanoparticles, passivated by oleic acid and dispersed in octane solution, onto three different substrates (Si, Si3N4, and SiO2) is investigated. The average nanoparticle size is 10 nm, with a size variation (σ) less than 5 %. The adsorption of particles is strongly dependent on both the type of substrate and the particle concentration in solution. By a single‐dipping process, we have obtained a maximum coverage of 0.45 on a Si substrate, but much less on other substrates (0.19 on Si3N4 and 0.14 on SiO2). The particle coverage was drastically increased by the multiple‐adsorption process, where the process of dipping and drying was repeated multiple times. With this process, we can obtain a maximum particle coverage of about 0.76 on a Si substrate and 0.61 on a thermally grown SiO2 substrate. 相似文献
4.
Gonglei Shao Xiong‐Xiong Xue Binbin Wu Yung‐Chang Lin Miray Ouzounian Travis Shihao Hu Yeqing Xu Xiao Liu Shisheng Li Kazu Suenaga Yexin Feng Song Liu 《Advanced functional materials》2020,30(5)
Crystal phase control still remains a challenge for the precise synthesis of 2D layered metal dichalcogenide (LMD) materials. The T′ phase structure has profound influences on enhancing electrical conductivity, increasing active sites, and improving intrinsic catalytic activity, which are urgently needed for enhancing hydrogen evolution reaction (HER) activity. Theoretical calculations suggest that metastable T′ phase 2D Sn1?xWxS2 alloys can be formed by combining W with 1T tin disulfide (SnS2) as a template to achieve a semiconductor‐to‐metallic transition. Herein, 2D Sn1?xWxS2 alloys with varying x are prepared by adjusting the molar ratio of reactants via hydrothermal synthesis, among which Sn0.3W0.7S2 displays a maximum of concentration of 81% in the metallic phase and features a distorted octahedral‐coordinated metastable 1T′ phase structure. The obtained 1T′‐Sn0.3W0.7S2 has high intrinsic electrical conductivity, lattice distortion, and defects, showing a prominently improved HER catalytic performance. Metallic Sn0.3W0.7S2 coupled with carbon black exhibits at least a 215‐fold improvement compared to pristine SnS2. It has excellent long‐term durability and HER activity. This work reveals a general phase transition strategy by using T phase materials as templates and merging heteroatoms to achieve synthetic metastable phase 2D LMDs that have a significantly improved HER catalytic performance. 相似文献
5.
Fabiola Liscio Silvia Milita Cristiano Albonetti Pasquale D'Angelo Antonietta Guagliardi Norberto Masciocchi Raffaele Guido Della Valle Elisabetta Venuti Aldo Brillante Fabio Biscarini 《Advanced functional materials》2012,22(5):943-953
A multiscale investigation of N,N′‐bis(n‐octyl)‐x:y, dicyanoperylene‐3,4:9,10‐bis(dicarboximide), PDI8‐CN2, shows the same molecular arrangement in the bulk and in thin films sublimated on SiO2/Si wafers. Non‐conventional powder diffraction methods and theoretical calculations concur to provide a coherent picture of the crystalline structure. X‐ray diffraction (XRD) and atomic force microscopy (AFM) analyses of films of different thickness deposited at different substrate temperatures indicate the existence of two temperature‐dependent deposition regimes: a low‐temperature (room temperature) regime and a high‐temperature (80–120 °C) one, each characterized by different growth mechanisms. These mechanisms eventually result in different morphological and structural features of the films, which appear to be highly correlated with the trend of the electrical parameters that are measured in PDI8‐CN2‐based field‐effect transistors. 相似文献
6.
Watermelon‐Like Structured SiOx–TiO2@C Nanocomposite as a High‐Performance Lithium‐Ion Battery Anode
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Zhaolin Li Hailei Zhao Pengpeng Lv Zijia Zhang Yang Zhang Zhihong Du Yongqiang Teng Lina Zhao Zhiming Zhu 《Advanced functional materials》2018,28(31)
A unique watermelon‐like structured SiOx–TiO2@C nanocomposite is synthesized by a scalable sol–gel method combined with carbon coating process. Ultrafine TiO2 nanocrystals are uniformly embedded inside SiOx particles, forming SiOx–TiO2 dual‐phase cores, which are coated with outer carbon shells. The incorporation of TiO2 component can effectively enhance the electronic and lithium ionic conductivities inside the SiOx particles, release the structure stress caused by alloying/dealloying of Si component and maximize the capacity utilization by modifying the Si–O bond feature and decreasing the O/Si ratio (x‐value). The synergetic combination of these advantages enables the synthesized SiOx–TiO2@C nanocomposite to have excellent electrochemical performances, including high specific capacity, excellent rate capability, and stable long‐term cycleability. A stable specific capacity of ≈910 mAh g?1 is achieved after 200 cycles at the current density of 0.1 A g?1 and ≈700 mAh g?1 at 1 A g?1 for over 600 cycles. These results suggest a great promise of the proposed particle architecture, which may have potential applications in the improvement of various energy storage materials. 相似文献
7.
Carrier Modulation of Ambipolar Few‐Layer MoTe2 Transistors by MgO Surface Charge Transfer Doping
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Wei Luo Mengjian Zhu Gang Peng Xiaoming Zheng Feng Miao Shuxin Bai Xue‐Ao Zhang Shiqiao Qin 《Advanced functional materials》2018,28(15)
Semiconducting molybdenum ditelluride (2H‐MoTe2), a fast‐emerging 2D material with an appropriate band gap and decent carrier mobility, is configured as field‐effect transistors and is the focus of substantial research interest, showing hole‐dominated ambipolar characteristics. Here, carrier modulation of ambipolar few‐layer MoTe2 transistors is demonstrated utilizing magnesium oxide (MgO) surface charge transfer doping. By carefully adjusting the thickness of MgO film and the number of MoTe2 layers, the carrier polarity of MoTe2 transistors from p‐type to n‐type can be reversely controlled. The electron mobility of MoTe2 is significantly enhanced from 0.1 to 20 cm2 V?1 s?1 after 37 nm MgO film doping, indicating a greatly improved electron transport. The effective carrier modulation enables to achieve high‐performance complementary inverters with high DC gain of >25 and photodetectors based on few‐layer MoTe2 flakes. The results present an important advance toward the realization of electronic and optoelectronic devices based on 2D transition‐metal dichalcogenide semiconductors. 相似文献
8.
Fully Transparent p‐MoTe2 2D Transistors Using Ultrathin MoOx/Pt Contact Media for Indium‐Tin‐Oxide Source/Drain
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Yongjae Cho Ji Hoon Park Minju Kim Yeonsu Jeong Jongtae Ahn Taeyoung Kim Hyunyong Choi Yeonjin Yi Seongil Im 《Advanced functional materials》2018,28(39)
Since transition metal dichalcogenide (TMD) semiconductors are found as 2D van der Waals materials with a discrete energy bandgap, many 2D‐like thin field effect transistors (FETs) and PN diodes are reported as prototype electrical and optoelectronic devices. As a potential application of display electronics, transparent 2D FET devices are also reported recently. Such transparent 2D FETs are very few in report, yet no p‐type channel 2D‐like FETs are seen. Here, 2D‐like thin transparent p‐channel MoTe2 FETs with oxygen (O2) plasma‐induced MoOx/Pt/indium‐tin‐oxide (ITO) contact are reported for the first time. For source/drain contact, 60 s short O2 plasma and ultrathin Pt‐deposition processes on MoTe2 surface are sequentially introduced before ITO thin film deposition and patterning. As a result, almost transparent 2D FETs are obtained with a decent mobility of ≈5 cm2 V?1 s?1, a high ON/OFF current ratio of ≈105, and 70% transmittance. In particular, for normal MoTe2 FETs without ITO, O2 plasma process greatly improves the hole injection efficiency and device mobility (≈60 cm2 V?1 s?1), introducing ultrathin MoOx between Pt source/drain and MoTe2. As a final device application, a photovoltaic current modulator, where the transparent FET stably operates as gated by photovoltaic effects, is integrated. 相似文献
9.
Junyong Wang Xin Luo Shisheng Li Ivan Verzhbitskiy Weijie Zhao Shunfeng Wang Su Ying Quek Goki Eda 《Advanced functional materials》2017,27(14)
Distorted octahedral T′ phase of MoTe2 has recently attracted significant interest due to its predicted topological states and novel charge transport properties. Here, we report a nondestructive method for determining the crystal orientation of few‐layer T′‐MoTe2 flakes by polarized Raman spectroscopy. The experimentally observed Raman modes are assigned to eigenmodes of vibrations predicted by density functional theory calculations. Polarized Raman measurements reveal four distinct types of angle‐dependent intensity variations. From group theory, it can be deduced that the intensity of the Bg mode reaches a maximum in the configuration when the polarization vector of the incident light is either parallel or orthogonal to the metal–metal zigzag chain direction. The intensity variation of the Bg mode cannot be used to unambiguously determine the crystal orientation. Using electron diffraction analysis, it is demonstrated that the intensity of the Ag mode at around 162 cm?1 reaches a maximum when the polarization vector of the incident light is parallel to the metal–metal chain direction in the configuration. Furthermore, a simple method is proposed for identifying crystal orientation in nonpolarized Raman spectroscopy. 相似文献
10.
A very simple polydimethylsiloxane (PDMS) pattern‐transfer method is devised, called buffered‐oxide etchant (BOE) printing. The mechanism of pattern transfer is investigated, by considering the strong adhesion between the BOE‐treated PDMS and the SiO2 substrate. PDMS patterns from a few micrometers to sub‐micrometer size are transferred to the SiO2 substrate by just pressing a stamp that has been immersed in BOE solution for a few minutes. The patterned PDMS layers work as perfect physical and chemical passivation layers in the fabrication of metal electrodes and V2O5 nanowire channels, respectively. Interestingly, a second stamping of the BOE‐treated PDMS on the SiO2 substrate pre‐patterned with metal as well as PDMS results in a selective transfer of the PDMS patterns only to the bare SiO2. In this way, the fabrication of a device structure consisting of two Au electrodes and V2O5 nanowire network channels is possible; non‐ohmic semiconducting I–V characteristics, which can be modeled by serially connected percolation, are observed. 相似文献
11.
On the Relation between Morphology and FET Mobility of Poly(3‐alkylthiophene)s at the Polymer/SiO2 and Polymer/Air Interface
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Wibren D. Oosterbaan Jean‐Christophe Bolsée Linjun Wang Veerle Vrindts Laurence J. Lutsen Vincent Lemaur David Beljonne Lars Thomsen Jean V. Manca Dirk J. M. Vanderzande 《Advanced functional materials》2014,24(14):1994-2004
The influence of the interface of the dielectric SiO2 on the performance of bottom‐contact, bottom‐gate poly(3‐alkylthiophene) (P3AT) field‐effect transistors (FETs) is investigated. In particular, the operation of transistors where the active polythiophene layer is directly spin‐coated from chlorobenzene (CB) onto the bare SiO2 dielectric is compared to those where the active layer is first spin‐coated then laminated via a wet transfer process such that the film/air interface of this film contacts the SiO2 surface. While an apparent alkyl side‐chain length dependent mobility is observed for films directly spin‐coated onto the SiO2 dielectric (with mobilities of ≈10?3 cm2 V?1 s?1 or less) for laminated films mobilities of 0.14 ± 0.03 cm2 V?1 s?1 independent of alkyl chain length are recorded. Surface‐sensitive near edge X‐ray absorption fine structure (NEXAFS) spectroscopy measurements indicate a strong out‐of‐plane orientation of the polymer backbone at the original air/film interface while much lower average tilt angles of the polymer backbone are observed at the SiO2/film interface. A comparison with NEXAFS on crystalline P3AT nanofibers, as well as molecular mechanics and electronic structure calculations on ideal P3AT crystals suggest a close to crystalline polymer organization at the P3AT/air interface of films from CB. These results emphasize the negative influence of wrongly oriented polymer on charge carrier mobility and highlight the potential of the polymer/air interface in achieving excellent “out‐of‐plane” orientation and high FET mobilities. 相似文献
12.
Jangdae Youn Geetha R. Dholakia Hui Huang Jonnathan W. Hennek Antonio Facchetti Tobin J. Marks 《Advanced functional materials》2012,22(9):1856-1869
The performance of bottom‐contact thin‐film transistor (TFT) structures lags behind that of top‐contact structures owing to the far greater contact resistance. The major sources of the contact resistance in bottom‐contact TFTs are believed to reflect a combination of non‐optimal semiconductor growth morphology on the metallic contact surface and the limited available charge injection area versus top‐contact geometries. As a part of an effort to understand the sources of high charge injection barriers in n‐channel TFTs, the influence of thiol metal contact treatment on the molecular‐level structures of such interfaces is investigated using hexamethyldisilazane (HMDS)‐treated SiO2 gate dielectrics. The focus is on the self‐assembled monolayer (SAM) contact surface treatment methods for bottom‐contact TFTs based on two archetypical n‐type semiconductors, α,ω‐diperfluorohexylquarterthiophene (DFH‐4T) and N,N′bis(n‐octyl)‐dicyanoperylene‐3,4:9,10‐bis(dicarboximide) (PDI‐8CN2). TFT performance can be greatly enhanced, to the level of the top contact device performance in terms of mobility, on/off ratio, and contact resistance. To analyze the molecular‐level film structural changes arising from the contact surface treatment, surface morphologies are characterized by atomic force microscopy (AFM) and scanning tunneling microscopy (STM). The high‐resolution STM images show that the growth orientation of the semiconductor molecules at the gold/SAM/semiconductor interface preserves the molecular long axis orientation along the substrate normal. As a result, the film microstructure is well‐organized for charge transport in the interfacial region. 相似文献
13.
Dan Yang Xiaozong Hu Minghao Zhuang Yao Ding Shasha Zhou Aoju Li Yiwei Yu Huiqiao Li Zhengtang Luo Lin Gan Tianyou Zhai 《Advanced functional materials》2018,28(26)
Inversion symmetry broken 3R phase semiconducting transition metal dichalcogenides (TMDC) have huge potential applications in many novel fields, such as valleytronics and nonlinear optics for the strong spin–orbit coupling and particularly the persistent noncentrosymmetric structure regardless the layer numbers, in stark contrast to the strict layer number requirement in other phases. Unfortunately, the fabrication of 3R phase TMDC is still a huge task to date. Molybdenum telluride (MoTe2) attracts increasing interest in recent years due to the easy transition between its various phases and its narrow bandgap close to silicon. However, the weak Mo–Te bond and the small energy imparity among phases make it a big challenge to obtain pure‐phase single crystalline MoTe2, especially; it is still a virgin land to obtain two‐dimensional (2D) 3R‐MoTe2. Here, by rational controlling the deposition temperature and tellurization velocity, for the first time high quality 2D 3R‐MoTe2 flakes are synthesized via chemical vapor deposition from a MoCl5 precursor. Scanning transmission electron microscopy unambiguously reveals the 3R stacking mode of as‐synthesized MoTe2. Second harmonic generation measurement confirms the excellent odd/even layer‐independent frequency conversion efficiency. Besides, the outstanding intrinsic infrared detection ability of as‐synthesized 3R‐MoTe2 is demonstrated as well. 相似文献
14.
NIR Light‐Triggered Degradable MoTe2 Nanosheets for Combined Photothermal and Chemotherapy of Cancer
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Ning Ma Ming‐Kang Zhang Xiao‐Shuang Wang Lu Zhang Jun Feng Xian‐Zheng Zhang 《Advanced functional materials》2018,28(31)
Telluride molybdenum (MoTe2) nanosheets with wide near‐infrared (NIR) absorbance are functionalized with polyethylene glycol‐cyclic arginine‐glycine‐aspartic acid tripeptide (PEG‐cRGD). After loading a chemotherapeutic drug (doxorubicin, DOX), MoTe2‐PEG‐cRGD/DOX is used for combined photothermal therapy and chemotherapy. With the high photothermal conversion efficiency, MoTe2‐PEG‐cRGD/DOX exhibits favorable cells killing ability under NIR irradiation. Owing to the cRGD‐mediated specific tumor targeting, MoTe2‐PEG‐cRGD/DOX shows efficient accumulation in tumors to induce a strong tumor ablation effect. MoTe2‐PEG‐cRGD nanosheets, which are relatively stable in the circulation, could be degraded under NIR ray. The in vitro and in vivo experimental results demonstrate that this theranostic nanoagent, which could accumulate in tumors to allow photothermal imaging and combined therapy, is readily degradable in normal organs to enable rapid excretion and avoid long‐term retention/toxicity, holding great potential to treat tumor effectively. 相似文献
15.
Well‐aligned nanocrystalline (nc)‐Si/SiOx composite nanowires have been deposited on various substrates at 120 °C using SiCl4/H2 in a hot‐filament chemical vapor deposition reactor. Structural and compositional analyses reveal that silicon nanocrystals are embedded in the amorphous SiOx nanowires. The nc‐Si/SiOx composite nanowires are transparent in the range 500–900 nm. Photoluminescence spectra of the nc‐Si/SiOx composite nanowires have a broad emission band, ranging from 420 to 525 nm. Water vapor from the chamber wall plays a crucial role in the formation of the well‐aligned nanowires. A possible mechanism for the formation of the composite nanowires is suggested. 相似文献
16.
A. N. Karpov D. V. Marin V. A. Volodin J. Jedrzejewski G. A. Kachurin E. Savir N. L. Shwartz Z. Sh. Yanovitskaya I. Balberg Y. Goldstein 《Semiconductors》2008,42(6):731-736
Deposition of SiO x layers of variable composition onto silicon wafers was performed by co-sputtering of spaced Si and SiO2 targets in argon plasma. Coordinate dependences of the thickness and refractive index of separately deposited Si and SiO2 layers and the SiO x layer grown during co-sputtering of targets were determined using optical techniques. It was shown that the SiO x layer composition is not equal to a simple sum of thicknesses of separately deposited Si and SiO2 layers. The coordinate dependences of the Si and SiO2 layer thicknesses were calculated. To fit the calculated and experimental data, it is necessary to assume that no less than 10% of silicon is converted to dioxide during co-sputtering. A comparison of the coordinate dependences of the IR absorbance in SiO2 and SiO x layers with experimental ellipsometric data confirmed the presence of excess oxygen in the SiO x layer. Taking into account such partial oxidation of sputtered silicon, composition isolines in the substrate plane were calculated. After annealing of the SiO x layer at 1200°C, photoluminescence was observed in a wafer area predicted by calculations, which was caused by the formation of quantum-size Si nanocrystallites. The photoluminescence intensity was maximum at x = 1.78 ± 0.3, which is close to the composition optimum for ion-beam synthesis of nanocrystals. 相似文献
17.
Kyunghee Choi Young Tack Lee Jin Sung Kim Sung‐Wook Min Youngsuk Cho Atiye Pezeshki Do Kyung Hwang Seongil Im 《Advanced functional materials》2016,26(18):3146-3153
As one of the emerging new transition‐metal dichalcogenides materials, molybdenum ditelluride (α‐MoTe2) is attracting much attention due to its optical and electrical properties. This study fabricates all‐2D MoTe2‐based field effect transistors (FETs) on glass, using thin hexagonal boron nitride and thin graphene in consideration of good dielectric/channel interface and source/drain contacts, respectively. Distinguished from previous works, in this study, all 2D FETs with α‐MoTe2 nanoflakes are dual‐gated for driving higher current. Moreover, for the present 2D dual gate FET fabrications on glass, all thermal annealing and lithography processes are intentionally exempted for fully non‐lithographic method using only van der Waal's forces. The dual‐gate MoTe2 FET displays quite a high hole and electron mobility over ≈20 cm2 V?1 s?1 along with ON/OFF ratio of ≈105 in maximum as an ambipolar FET and also demonstrates high drain current of a few tens‐to‐hundred μA at a low operation voltage. It appears promising enough to drive organic light emitting diode pixels and NOR logic functions on glass. 相似文献
18.
Combinatorial Study of Temperature‐Dependent Nanostructure and Electrical Conduction of Polymer Semiconductors: Even Bimodal Orientation Can Enhance 3D Charge Transport
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Sangsik Park Moo Hyung Lee Kwang Seok Ahn Hyun Ho Choi Jihye Shin Jie Xu Jianguo Mei Kilwon Cho Zhenan Bao Dong Ryeol Lee Moon Sung Kang Do Hwan Kim 《Advanced functional materials》2016,26(26):4627-4634
Temperature‐dependent (80–350 K) charge transport in polymer semiconductor thin films is studied in parallel with in situ X‐ray structural characterization at equivalent temperatures. The study is conducted on a pair of isoindigo‐based polymers containing the same π‐conjugated backbone with different side chains: one with siloxane‐terminated side chains (PII2T‐Si) and the other with branched alkyl‐terminated side chains (PII2T‐Ref). The different chemical moiety in the side chain results in a completely different film morphology. PII2T‐Si films show domains of both edge‐on and face‐on orientations (bimodal orientation) while PII2T‐Ref films show domains of edge‐on orientation (unimodal orientation). Electrical transport properties of this pair of polymers are also distinctive, especially at high temperatures (>230 K). Smaller activation energy (E A) and larger pre‐exponential factor (μ 0) in the mobility‐temperature Arrhenius relation are obtained for PII2T‐Si films when compared to those for PII2T‐Ref films. The results indicate that the more effective transport pathway is formed for PII2T‐Si films than for the other, despite the bimodally oriented film structure. The closer π–π packing distance, the longer coherence length of the molecular ordering, and the smaller disorder of the transport energy states for PII2T‐Si films altogether support the conduction to occur more effectively through a system with both edge‐on and face on orientations of the conjugated molecules. Reminding the 3D nature of conduction in polymer semiconductor, our results suggest that the engineering rules for advanced polymer semiconductors should not simply focus on obtaining films with conjugated backbone in edge‐on orientation only. Instead, the engineering should also encounter the contribution of the inevitable off‐directional transport process to attain effective transport from polymer thin films. 相似文献
19.
Ruixia Wu Quanyang Tao Weiqi Dang Yuan Liu Bo Li Jia Li Bei Zhao Zhengwei Zhang Huifang Ma Guangzhuang Sun Xidong Duan Xiangfeng Duan 《Advanced functional materials》2019,29(12)
2D metals have attracted considerable recent attention for their special physical properties, such as charge density waves, magnetism, and superconductivity. However, despite some recent efforts, the synthesis of ultrathin 2D metals nanosheets down to monolayer thickness remains a significant challenge. Herein, by using atomically flat 2D WSe2 or WS2 as the growth substrate, the synthesis of atomically thin 2D metallic MTe2 (M = V, Nb, Ta) single crystals with the thickness down to the monolayer regime and the creation of atomically thin MTe2/WSe2 (WS2) vertical heterojunctions is reported. Comparison with the growth on the SiO2/Si substrate under the same conditions reveals that the utilization of the dangling‐bond‐free WSe2 or WS2 as the van der Waals epitaxy substrates is crucial for the successful realization of atomically thin MTe2 (M = V, Nb, Ta) nanosheets. It is further shown that the epitaxial grown 2D metals can function as van der Waals contacts for 2D semiconductors with little interface damage and improved electronic performance. This study defines a robust van der Waals epitaxy pathway to ultrathin 2D metals, which is essential for fundamental studies and potential technological applications of this new class of materials at the 2D limit. 相似文献
20.
Do Yun Kim Erwin Guijt Ren A. C. M. M. van Swaaij Miro Zeman 《Progress in Photovoltaics: Research and Applications》2015,23(6):671-684
In this study, deposition conditions for making a‐SiOx:H are investigated systematically in order to obtain a high band gap material. We found that at given optical band gap, a‐SiOx:H with favorable opto‐electronic properties can be obtained when deposited using low CO2 flow rates and deposition pressures. We also found that a low radio frequency power density is required in order to limit the effect of ion bombardment on the material properties of i‐a‐SiOx:H and thereby the solar cell performance. In addition, by decreasing the heater temperature from 300 to 200°C when making the i‐a‐SiOx:H, the Voc can be increased. We employed optimized p‐doped and n‐doped a‐SiOx:H films into the p‐i‐n solar cells, and as a consequence, a high Voc of over 1 V and high fill factor (FF) are obtained. When depositing on texture‐etched ZnO:Al substrates, a high efficiency a‐SiOx:H single junction solar cell having a high Voc × FF product of 0.761 (Voc: 1.042 V, Jsc: 10.3 mA/cm2, FF: 0.73, efficiency: 7.83%) was obtained. The a‐SiOx:H solar cell shows comparable light degradation characteristics to standard a‐Si:H solar cells. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献