Electrical Properties of Black Phosphorus Single Crystals

Akahama, Yuichi; Endo, S.; Narita, Shin‐ichiro

doi:10.1143/jpsj.52.2148

Cited by 281 publications

(287 citation statements)

References 7 publications

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“…This  value for few-layer phosphorene is notably smaller than the value in other 2D materials 32 and bulk black phosphorus 11 , but agrees with that in monolayer MoS2…”

supporting

confidence: 74%

Black phosphorus field-effect transistors

et al. 2014

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Black phosphorus is a layered material in which individual atomic layers are stacked together by Van der Waals interactions, much like bulk graphite 1 . Inside a single layer, each phosphorus atom is covalently bonded with three adjacent phosphorus atoms to form a puckered honeycomb structure [2][3][4] (Fig. 1a). The three bonds take up all three valence electrons of phosphorus, so unlike graphene 5,6 a monolayer black phosphorus (termed "phosphorene") is a semiconductor with a predicted direct band gap of ~ 2 eV at the Γ point of the first Brillouin zone 7 . For few-layer phosphorene, interlayer interactions reduce the band gap for each layer 3 added, and eventually reach ~ 0.3 eV (refs 8-11) for bulk black phosphorus. The direct gap also moves to the Z point as a consequence 7,12 . Such a band structure provides a much needed gap for the field-effect transistor (FET) application of two dimensional (2D) materials such as graphene, and the thickness-dependent direct band gap may lead to potential applications in optoelectronics, especially in the infrared regime. In addition, observations of phase transition from semiconductor to metal 13,14 and superconductor under high pressure 15,16 We next fabricate few-layer phosphorene FETs with a back-gate electrode (see Fig. 2a). A scotch tape based mechanical exfoliation method is employed to peel thin flakes from bulk crystal onto degenerately doped silicon wafer covered with a layer of thermally grown silicon dioxide. Optical microscopy and atomic force microscopy (AFM) are used to hunt thin flake samples and determine their thickness (Fig. 2a). The switching behaviour of our few-layer phosphorene transistor at room temperature is characterized in vacuum (~ 10 -6 mBar), in a configuration depicted in -30 V to 0 V, the channel switches from "on" state to "off" state, and a drop in drain current by a factor of ~ 10 5 is observed. The measured drain current modulation is 4 orders of magnitude larger than that in graphene (due to its lack of bandgap), and 5 approaches the value recently reported in MoS2 devices 17 . Such a high drain current modulation makes black phosphorus thin film a promising material for applications in digital electronics 22 . Similar switching behaviour (with varying drain current modulation) is observed on all black phosphorous thin film transistors with thicknesses up to 50 nm. We note that the "on" state current of our devices has not yet reached saturation, due to the fact that the doping level is limited by the break-down electric field of the SiO2 back-gate dielectric. It is therefore possible to achieve even higher drain current modulation by using high-k materials as gate dielectrics for higher doping. Meanwhile, a subthreshold swing (SS) of ~ 5 V/decade is observed, which is much larger than the SS in commercial Si-based devices (~ 70 mV/decade).We note that the SS in our devices varies from sample to sample (from ~ 3.7 V/decade to ~ 13.3 V/decade), and is on the same order of magnitude as reported in multilayerMoS2 devices with a simila...

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“…This  value for few-layer phosphorene is notably smaller than the value in other 2D materials 32 and bulk black phosphorus 11 , but agrees with that in monolayer MoS2…”

supporting

confidence: 74%

Black phosphorus field-effect transistors

et al. 2014

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“…Table II lists the calculated carrier effective masses along the x, y, and z directions, where we find that the one along the z direction is the smallest, especially for the case of holes. Such small effective mass would set a crucial precondition for BP to exhibit a high carrier mobility, which is confirmed by the experimental results [42] and suggests that the carrier transport of BP along the z direction is quite favorable and may be beneficial to its thermoelectric performance. On the other hand, we see the DOS of BP at the bottom of conduction band exhibits a sharper peak than that at the top of valance band.…”

Section: Lattice Structure and Electronic Properties Of Bpsupporting

confidence: 62%

High thermoelectric performance can be achieved in black phosphorus

et al. 2016

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Few-layer black phosphorus has recently emerged as a promising candidate for novel electronic and optoelectronic device. Here we demonstrate by first-principles calculations and Boltzmann theory that, black phosphorus could also have potential thermoelectric applications and a fair ZT value of 1.1 can be achieved at elevated temperature. Moreover, such value can be further increased to 5.4 by substituting P atom with Sb atom, giving nominal formula of P 0.75 Sb 0.25 . Our theoretical work suggests that high thermoelectric performance can be achieved without using complicated crystal structure or seeking for low-dimensional systems.

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“…At T Շ 200 K, the VRH model shows good fitting with the data. r deviates from the VRH prediction at T տ 200 K, probably due to thermal activated band transport, as the acceptor activation energy is $18 meV, 32 and acoustic phonons scattering grows to be competitive with the VRH process at high temperatures. When temperature goes below $50 K, the interactions among conducting electrons may need to be considered (the Efros model).…”

Section: -3mentioning

confidence: 79%

Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

Liu

Choe

Chen

et al. 2017

Applied Physics Letters

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Black phosphorus (BP) is a layered semiconductor with a high mobility of up to $1000 cm 2 V À1 s À1 and a narrow bandgap of $0.3 eV, and shows potential applications in thermoelectrics. In stark contrast to most other layered materials, electrical and thermoelectric properties in the basal plane of BP are highly anisotropic. To elucidate the mechanism for such anisotropy, we fabricated BP nanoribbons ($100 nm thick) along the armchair and zigzag directions, and measured the transport properties. It is found that both the electrical conductivity and Seebeck coefficient increase with temperature, a behavior contradictory to that of traditional semiconductors. The three-dimensional variable range hopping model is adopted to analyze this abnormal temperature dependency of electrical conductivity and Seebeck coefficient. The hopping transport of the BP nanoribbons, attributed to high density of trap states in the samples, provides a fundamental understanding of the anisotropic BP for potential thermoelectric applications. Published by AIP Publishing. [http://dx

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Electrical Properties of Black Phosphorus Single Crystals

Cited by 281 publications

References 7 publications

Black phosphorus field-effect transistors

Black phosphorus field-effect transistors

High thermoelectric performance can be achieved in black phosphorus

Variable range hopping electric and thermoelectric transport in anisotropic black phosphorus

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