Temperature dependence of the energy bandgap of two-dimensional hexagonal boron nitride probed by excitonic photoluminescence

Du, Xiaozhang; Frye, Clint D.; Edgar, James H.; Lin, J. Y.; Jiang, H. X.

doi:10.1063/1.4863823

Cited by 14 publications

(15 citation statements)

References 30 publications

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“…Adjusting the temperature-dependent data recorded up to 800K in Ref. [27] (symbols, Fig.2(c)), we obtain Ω=68±2 meV. Compared to the absolute maximum of the phonon dispersion of 200 meV in hBN [16], we obtain a ratio of 0.34, significantly lower than the usual one-half found in cubic semiconductors [5].…”

Section: Electronic Bandgapmentioning

confidence: 57%

Isotope engineering of van der Waals interactions in hexagonal boron nitride

et al. 2017

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Hexagonal boron nitride is a model lamellar compound where weak, non-local van der Waals interactions ensure the vertical stacking of two-dimensional honeycomb lattices made of strongly bound boron and nitrogen atoms. We study the isotope engineering of lamellar compounds by synthesizing hexagonal boron nitride crystals with nearly pure boron isotopes (B and B) compared to those with the natural distribution of boron (20 at%B and 80 at% B). On the one hand, as with standard semiconductors, both the phonon energy and electronic bandgap varied with the boron isotope mass, the latter due to the quantum effect of zero-point renormalization. On the other hand, temperature-dependent experiments focusing on the shear and breathing motions of adjacent layers revealed the specificity of isotope engineering in a layered material, with a modification of the van der Waals interactions upon isotope purification. The electron density distribution is more diffuse between adjacent layers inBN than in BN crystals. Our results open perspectives in understanding and controlling van der Waals bonding in layered materials.

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Section: Electronic Bandgapmentioning

confidence: 57%

Isotope engineering of van der Waals interactions in hexagonal boron nitride

et al. 2017

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“…Hexagonal boron nitride (h-BN) has been under intensive investigation in recent years due to its unique physical properties including wide bandgap energy ($6.5 eV), high emission efficiency, large thermal conductivity, high chemical and temperature stability, as well as large neutron capture cross-section of the isotope boron-10. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] It is a very promising material for deep ultraviolet photonic devices [1][2][3][4][5][6][7][8][9][10][11][12] and neutron detector applications. [13][14][15] However, the development of epitaxial growth of wafer-scale semiconducting h-BN, which is a prerequisite for practical device fabrication, is still in the early stage and will benefit from a better understanding of its fundamental properties.…”

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confidence: 99%

“…Triethylboron (TEB) and NH 3 were serving as B and N sources, respectively. [8][9][10][11][12] The excitation source in the photoluminescence (PL) measurement system is a frequencyquadruped Ti-sapphire laser (197 nm lasing wavelength, 76 MHz repetition rate, 100 fs pulse width, and average optical power of $1 mW). A monochromator (1.3 m) collects and disperses the PL signal, which was then detected by a microchannel plate photomultiplier tube.…”

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confidence: 99%

“…A monochromator (1.3 m) collects and disperses the PL signal, which was then detected by a microchannel plate photomultiplier tube. 9,12 Figure 1 shows the room temperature PL spectra of h-BN epilayer samples grown under varying NH 3 flow rates from 0.2 to 1.5 standard liters per minute (SLM) during the MOCVD growth. All other growth conditions of these samples were identical.…”

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The origin of deep-level impurity transitions in hexagonal boron nitride

Lin

et al. 2015

Applied Physics Letters

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Deep ultraviolet photoluminescence (PL) emission spectroscopy has been employed to investigate the origin of the widely observed deep level impurity related donor-acceptor pair (DAP) transition with an emission peak near 4.1 eV in hexagonal boron nitride (h-BN). A set of h-BN epilayers were grown by metal-organic chemical vapor deposition (MOCVD) under different ammonia (NH 3) flow rates to explore the role of nitrogen vacancies (V N) in the deep-level transitions. The emission intensity of the DAP transition near 4.1 eV was found to decrease exponentially with an increase of the NH 3 flow rate employed during the MOCVD growth, implying that impurities involved are V N. The temperature-dependent PL spectra were measured from 10 K up to 800 K, which provided activation energies of $0.1 eV for the shallow impurity. Based on the measured energy level of the shallow impurity ($0.1 eV) and previously estimated bandgap value of about 6.5 eV for h-BN, we deduce a value of $2.3 eV for the deep impurity involved in this DAP transition. The measured energy levels together with calculation results and formation energies of the impurities and defects in h-BN suggest that V N and carbon impurities occupying the nitrogen sites, respectively, are the most probable shallow donor and deep acceptor impurities involved in this DAP transition.

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“…The lattice parameters along the c-axis and along the a-axis of the BN polycrystals increased from 6.7338 to 6.7505Å and from 2.5024 to 2.5384Å as the temperature increases from 300 to 360 K for each unit cell. On the other hand, the excitonic energy band gap of the hexagonal BN is reported to exhibit a negative temperature coefficient of ∼4.3 × 10 −4 eV/ ∘ K [13]. The latter value indicates an expected effect on the device parameters ( , ) associated with the narrowing of the energy band gap of BN.…”

Section: Resultsmentioning

confidence: 96%

Microwave Impedance Spectroscopy and Temperature Effects on the Electrical Properties of Au/BN/C Interfaces

Khanfar¹,

Qasrawi²,

Ghannam³

2017

Active and Passive Electronic Components

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In the current study, an Au/BN/C microwave back-to-back Schottky device is designed and characterized. The device morphology and roughness were evaluated by means of scanning electron and atomic force microscopy. As verified by the Richardson–Schottky current conduction transport mechanism which is well fitted to the experimental data, the temperature dependence of the current-voltage characteristics of the devices is dominated by the electric field assisted thermionic emission of charge carriers over a barrier height of ~0.87 eV and depletion region width of ~1.1 μm. Both the depletion width and barrier height followed an increasing trend with increasing temperature. On the other hand, the alternating current conductivity analysis which was carried out in the frequency range of 100–1400 MHz revealed the domination of the phonon assisted quantum mechanical tunneling (hopping) of charge carriers through correlated barriers (CBH). In addition, the impedance and power spectral studies carried out in the gigahertz-frequency domain revealed a resonance-antiresonance feature at frequency of ~1.6 GHz. The microwave power spectra of this device revealed an ideal band stop filter of notch frequency of ~1.6 GHz. The ac signal analysis of this device displays promising characteristics for using this device as wave traps.

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Temperature dependence of the energy bandgap of two-dimensional hexagonal boron nitride probed by excitonic photoluminescence

Cited by 14 publications

References 30 publications

Isotope engineering of van der Waals interactions in hexagonal boron nitride

Isotope engineering of van der Waals interactions in hexagonal boron nitride

The origin of deep-level impurity transitions in hexagonal boron nitride

Microwave Impedance Spectroscopy and Temperature Effects on the Electrical Properties of Au/BN/C Interfaces

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