Metal‐Ion‐Modified Black Phosphorus with Enhanced Stability and Transistor Performance

Guo, Zhinan; Chen, Si; Wang, Zhongzheng; Yang, Zhenyu; Liu, Fei; Xu, Yanhua; Wang, Jiahong; Yi, Ya Sha; Zhang, Han; Liao, Lei; Chu, Paul K.; Yu, Xue‐Feng

doi:10.1002/adma.201703811

Cited by 466 publications

(320 citation statements)

References 54 publications

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“…In each layer of BP, the lone pair electrons of phosphorus atoms interact with each other, forming conjugated π bonds at the surface and interlayer. During the metal evaporation, the evaporated Cu atoms have negative formation energy with the conjugated π bond of BP, indicating the spontaneous electron interaction between Cu and BP at the surface and interlayer . The thermally favored formation of Cu‐P interactions also promotes the penetration of Cu int between BP layers…”

Section: Resultsmentioning

confidence: 99%

“…Contact engineering and surface doping have been applied to modulate the carrier type and achieve complementary 2D material transistors . In recent studies, n‐type BP transistors were fabricated by utilizing contact metals with low work function, such as aluminum (Al) and scandium (Sc) .…”

Section: Introductionmentioning

confidence: 99%

“…These low‐work‐function metal contacts hold the BP Fermi level close to the conduction band minimum with low Schottky barrier height (SBH) for electrons. Except utilizing low‐work‐function metals, surface charge transfer offers another way for modulation doping . Surface functionalization with cesium carbonate (Cs 2 CO 3 ) is reported to strongly electron dope BP, where the BP FETs exhibit transition from ambipolar to n‐type transport property with the increase of the thickness of Cs 2 CO 3 .…”

Section: Introductionmentioning

confidence: 99%

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Interstitial copper‐doped edge contact for n‐type carrier transport in black phosphorus

Lin

Wang

Guo

et al. 2019

InfoMat

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Black phosphorus (BP) has been shown as a promising two‐dimensional (2D) material for electronic devices owing to its high carrier mobility. To realize complementary electronic circuits with 2D materials, it is important to fabricate both n‐type and p‐type transistors with the same channel material. By engineering the contact region with copper (Cu)‐doped BP, here we demonstrate an n‐type carrier transport in BP field‐effect transistors (FETs), which usually exhibit strongly p‐type characteristics. Cu metal atoms are found to severely penetrate into the BP flakes, which forms interstitial Cu (Cuint)‐doped edge contact and facilitates the electron transport in BP. Our BP FETs in back‐gated configuration exhibit n‐type dominant characteristics with a high electron mobility of ~ 138 cm2 V−1 s−1 at room temperature. The Schottky barrier height for electrons is relatively low because of the edge contact between Cuint‐doped BP and pristine BP channel. The contact doping of BP by highly mobile Cu atoms gives rise to n‐type transport property of BP FETs. Furthermore, we demonstrate a p‐n junction on the same BP flake with asymmetric contact. This strategy on contact engineering can be further extended to other 2D materials.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Interstitial copper‐doped edge contact for n‐type carrier transport in black phosphorus

Lin

Wang

Guo

et al. 2019

InfoMat

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“…However, the absence of a bandgap limits its applications in electronic devices, and makes it diffi cult to achieve a high on/off ratio in FETs. [12][13][14] . [ 7,8 ] However, the carrier mobility is limited to ≈10 2 cm 2 V −1 s −1 .…”

Section: Monolayer Fetsmentioning

confidence: 99%

High‐Performance Field‐Effect Transistors Based on αP and βP

Montes

Schwingenschlögl

2019

Advanced Materials

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convert the puckered structure of αP into a buckled structure with hexagonal unit cell, giving rise to another 2D allotrope (derived from blue phosphorus; βP). [ 18 ] Based on fi rst-principles calculations, βP is as stable as αP, but is predicted to have very different electronic properties. While αP has a direct bandgap of ≈1 eV at the Γ point, the ≈2 eV bandgap of βP is indirect. The electronic states of both materials can be easily modulated by employing axial strain. [ 16,18 ] It may be possible to mechanically exfoliate βP from the bulk compound, while so far it only has been synthesized by molecular beam epitaxial growth on Au(111) substrate. [ 19 ] Both αP and βP have great potential in applications due to their extraordinary electronic and thermal transport characteristics. [ 20 ] In order to engineer nanostructured FETs, a series of strategies have been applied in the past, [21][22][23] including the use of nanotubes and nanoribbons. [24][25][26] Because of quantum confi nement and unique edge effects, nanoribbons exhibit many exploitable features, in particular from the electrical, optical, and magnetic point of view. [ 27,28 ] Nanoribbons of αP can be both metallic and semiconducting, depending on their crystallographic direction and the functionalization of the edges. [29][30][31] The electronic transport in metallic αP nanoribbons has been investigated theoretically, fi nding a robust negative differential resistance. [ 32 ] On the other hand, both armchair and zigzag βP nanoribbons are semiconducting, while the nature of the bandgap (direct or indirect) is different. [ 33,34 ] In order to establish the properties of αP and βP nanoribbons we study in this paper in a fi rst step their electronic structure. In a second step we propose a FET design based on connected armchair and zigzag nanoribbons cut out of a single sheet of αP or βP, which ensures atomically perfect junctions. We then characterize the performance of such devices by means of transport calculations using the nonequilibrium Green's function method.Our fi rst-principles calculations were based on density functional theory as implemented in the SIESTA code. [ 35,36 ] All structures were fully relaxed until the Hellman-Feynman forces had declined to less than 0.02 eV Å −1 . Double zeta plus polarization basis sets were employed, the core electrons were described by norm-conserving Troullier-Martins pseudopotentials, [ 37 ] and the exchange correlation functional was used for the generalized gradient approximation. The reciprocal space was sampled on a Monkhorst-Pack 1 × 1 × 10 k-mesh and the real space mesh refered to an energy cutoff of 200 Ry.Electron transport calculations were performed using the nonequilibrium Green's function method (SMEAGOL package [ 38,39 ] ). Semi-infi nite electrodes connected to the central The electronic properties of black and blue phosphorus nanoribbons are investigated, which enables the proposal of junction-free fi eld-effect transistors that comprise metallic armchair nanoribbons as electrodes and, in bet...

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“…However, intrinsic instability in BP due to its sensitivity to oxygen and water has set up a great barrier for its long‐term practical applications. Recently, several strategies had been demonstrated to improve the stability of BP, including covalent functionalization, surface coordination, protective encapsulation, metal ion modification and synchronous fluorination . Among these, synchronous fluorination can facilely deliver fluorinated phosphorene (FP) through one‐step synthesis process in electrochemical exfoliation.…”

Section: Introductionmentioning

confidence: 99%

All‐Optical Phosphorene Phase Modulator with Enhanced Stability Under Ambient Conditions

Wang

Zhang

Tang

et al. 2018

Laser & Photonics Reviews

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165

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All‐optical modulators, wherein signal light can be manipulated by another controlling light, have recently emerged as a promising perspective in all‐optical communications, interconnects and signal processing. Herein, by taking advantage of the strong light‐matter interaction and thickness‐dependent direct energy bandgap in few‐layer phosphorene, an all‐fiber all‐optical modulator based on a Mach–Zehnder interferometer comprising few‐layer fluorinated phosphorene‐deposited microfiber has been devised and further demonstrated with phase modulation ability. The phase shift of the signal light, capable of being converted into intensity modulation, could be readily controlled by the photothermal effect in phosphorene. A maximal phase shift of 8π is obtained at a control light of 290 mW, corresponding to a conversion efficiency of 0.029 π mW−1. The optical information carried by the control light is successfully copied towards the signal light with a modulation depth of 17 dB and a rise time constant of 2.5 ms. Stability under ambient conditions is enhanced significantly thanks to atomistic fluorination in phosphorene that can overcome drawbacks of easy oxidation of intrinsic phosphorene and maintain performance for a long term. This prototypical phosphorene‐based all‐optical phase modulator will have a great potential to be applied in all‐optical information processing and be integrated into optical fiber systems.

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Metal‐Ion‐Modified Black Phosphorus with Enhanced Stability and Transistor Performance

Cited by 466 publications

References 54 publications

Interstitial copper‐doped edge contact for n‐type carrier transport in black phosphorus

Interstitial copper‐doped edge contact for n‐type carrier transport in black phosphorus

High‐Performance Field‐Effect Transistors Based on αP and βP

All‐Optical Phosphorene Phase Modulator with Enhanced Stability Under Ambient Conditions

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