Superhigh out-of-plane piezoelectricity, low thermal conductivity and photocatalytic abilities in ultrathin 2D van der Waals heterostructures of boron monophosphide and gallium nitride†,Nanoscale

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Superhigh out-of-plane piezoelectricity, low thermal conductivity and photocatalytic abilities in ultrathin 2D van der Waals heterostructures of boron monophosphide and gallium nitride†
Nanoscale ( IF 5.8 ) Pub Date : 2019-10-15 , DOI: 10.1039/c9nr07586k
Manish Kumar Mohanta _{1,

2,

3} , Ashima Rawat _{1,

2,

3} , Dimple Dimple _{1,

2,

3} , Nityasagar Jena _{1,

2,

3} , Raihan Ahammed _{1,

2,

3} , Abir De Sarkar _{1,

2,

3}

Affiliation

A stable 2D van der Waals (vdW) heterobilayer, constituted by boron monophosphide (BP) and Gallium Nitride (GaN) monolayers, has been explored for different kinds of energy conversion and nanoelectronics. The nearly matched lattice constants of GaN and BP are commensurate with each other in their lattice structures. The out-of-plane inversion asymmetry coupled with the large difference in atomic charges between the GaN and BP monolayers induces in the heterobilayer a giant out-of-plane piezoelectric coefficient (|d₃₃|_max ≈ 40 pm V⁻¹), which is the highest ever reported in 2D materials of a finite thickness. It is much higher than the out-of-plane piezoelectric coefficient reported earlier in multilayered Janus transition metal dichalcogenide MXY (M = Mo, W; X, Y = S, Se, Te) (|d₃₃|_max = 10.57 pm V⁻¹). Such a high out-of-plane piezoelectricity found in a BP/GaN heterobilayer can bring about gigantic strain-tunable top gating effects in nanopiezotronic devices based on the same. Moreover, electron mobility (∼10⁴ cm² V⁻¹ s⁻¹) is much higher than that of transition metal dichalcogenides and conventional semiconductors. The origin of low lattice thermal conductivity (κ_L ∼ 25.25 W m⁻¹ K⁻¹) in BP/GaN at room temperature, which is lower than that of black phosphorene (78 W m⁻¹ K⁻¹), buckled arsenene (61 W m⁻¹ K⁻¹), BCN (90 W m⁻¹ K⁻¹), MoS₂ (34.5 W m⁻¹ K⁻¹) and WS₂ (32 W m⁻¹ K⁻¹) monolayers, has been systematically investigated via phonon dispersion, lattice thermal conductivity, phonon lifetime and mode Grüneisen parameters. The valence band maximum (VBM) and conduction band minimum (CBM) arising from GaN and BP monolayers respectively result in a type II vdW heterobilayer, which is found to be thermodynamically favorable for photocatalytic water splitting in both acidic and neutral media. The exciton binding energies are comparable to those of MoS₂ and C₃N₄ single layers, while the absorbance reaches as high as ∼10⁵ cm⁻¹ in the visible wavelength region. The emergence of high piezoelectricity, high carrier mobility, low lattice thermal conductivity and photocatalytic water splitting abilities in the proposed vdW heterobilayer signifies enormous potential for its versatile applications in nanoscale energy harvesting, e.g., nano-sensors in medical devices, future nanopiezotronics, 2D thermoelectrics and solar energy conversion.

中文翻译：

超薄二维一氧化硼和氮化镓的范德华异质结构中的超高面外压电性，低导热性和光催化能力†

由单磷化硼（BP）和氮化镓（GaN）单层构成的稳定的二维范德华（vdW）异质双层已被研究用于不同类型的能量转换和纳米电子学。GaN和BP的几乎匹配的晶格常数在其晶格结构中彼此相对应。外的平面中的反转不对称加上在heterobilayer巨型外的平面压电系数（在GaN和BP单层诱导之间的原子的电荷的大差| d ₃₃ |_最大≈40分V ^-1），这是有限厚度的2D材料中报告的最高值。这是大大高于外的平面中的压电系数早些时候在多层詹纳斯过渡金属二硫属化物MXY（M =钼，W; X，Y = S，硒，碲）报告（| d ₃₃ |_最大=下午10点57 V ^{- 1}）。在BP / GaN异质双分子层中发现的如此高的平面外压电能在基于纳米压电器件的纳米压电器件中带来巨大的应变可调顶部选通效应。而且，电子迁移率（〜10 ⁴ cm ² V ^-1 s ^-1）比过渡金属二卤化物和常规半导体的电子迁移率高得多。低晶格热导率的起源（κ_大号〜25.25脉冲W M ^-1 ķ ^-1）在BP /氮化镓在室温下，其比黑磷杂环的下部（78女男^-1 ķ ^-1），扣住arsenene（61女男^-1 ķ ^-1），BCN（90 W m ^-1 K ^-1），MoS ₂（34.5 W m ^-1 K ^-1）和WS ₂（32 W m ^-1 K ^-1）单层，已通过声子色散，晶格导热率，声子寿命和模式Grüneisen参数。由GaN和BP单层引起的价带最大值（VBM）和导带最小值（CBM）分别导致II型vdW异质双层，这在热力学上有利于在酸性和中性介质中进行光催化水分解。激子结合能与MoS ₂和C ₃ N ₄单层相当，而吸收率高达〜10 ⁵ cm ^-1在可见光波长区域。拟议的vdW异质双分子层中出现了高压电性，高载流子迁移率，低晶格热导率和光催化水分解能力，这表明其在纳米级能量收集中的广泛应用具有巨大潜力，例如医疗设备中的纳米传感器，未来的纳米压电，二维热电学。和太阳能转换。

更新日期：2019-11-21

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