Point defects induced work function modulation of β-Ga2O3

Tak, Bhera Ram; Dewan, Sheetal; Goyal, Anshu; Pathak, Ravi; Gupta, Vinay; Kapoor, A. K.; Nagarajan, S.; Singh, Rakesh Kumar

doi:10.1016/j.apsusc.2018.09.236

Cited by 89 publications

(47 citation statements)

References 24 publications

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“…The micro Raman spectrum of single-crystal Ga2O3 was recorded and is shown in figure 1b. In β-Ga2O3, only 15 phonon modes are Raman active among 27 modes at γ-point [22]. Here, 10 Raman modes have been observed from the spectral range of 100 to 900 cm -1 that are in good agreement with the reported phonon modes of monoclinic β-Ga2O3 [22,23].…”

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confidence: 86%

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Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

Kumar

Singh

Tak

et al. 2021

Applied Physics Letters

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Investigation of Seebeck coefficient in ultra-wide bandgap materials presents a challenge in measurement, nevertheless, it is essential for understanding fundamental transport mechanisms involved in electrical and thermal conduction. β-Ga2O3 is a strategic material for high power optoelectronic applications. Present work reports Seebeck coefficient measurement for single crystal Sn doped β-Ga2O3 in a wide temperature range (80-630 K). The non-monotonic trend with large magnitude and negative sign in the entire temperature range shows electrons are dominant carriers. The structural and Raman characterization confirms the single-phase and presence of low, mid, and high-frequency phonon modes, respectively. Temperature dependent (90-350 K) Hall effect measurement was carried out as supplementary study. Hall mobility showed µ T 1.12 for T<135 K and µ T −0.70 for T>220 K. Activation energies from Seebeck coefficient and conductivity analysis revealed presence of inter band conduction due to impurity defects. The room temperature Seebeck coefficient, power factor and thermal conductivity were found as 68.57 ±1.27 µV/K, 0.15 ±0.04 µW/K 2 cm and 14.2 ± 0.6 W/mK, respectively. The value of the figureof-merit for β-Ga2O3 was found to be ~ 0.01 (300 K).

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supporting

confidence: 86%

“…In β-Ga2O3, only 15 phonon modes are Raman active among 27 modes at γ-point [22]. Here, 10 Raman modes have been observed from the spectral range of 100 to 900 cm -1 that are in good agreement with the reported phonon modes of monoclinic β-Ga2O3 [22,23]. These phonon modes are divided into three broad-spectral regions.…”

supporting

confidence: 86%

Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

Kumar

Singh

Tak

et al. 2021

Applied Physics Letters

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“…Further experimental information can be found in reference. 33 X-ray diffraction (Philips Xpert Pro) having Cu Kα (λ = 1.54 Å) radiation was used for structural investigation of as-grown Ga2O3 thin film. Transmission Electron Microscopy (TEM) images were recorded using Titan G 2 80-300 ST system with a line resolution of 0.1 nm.…”

mentioning

confidence: 99%

High-temperature photocurrent mechanism of β-Ga2O3 based metal-semiconductor-metal solar-blind photodetectors

Tak

Garg

Dewan

et al. 2019

Journal of Applied Physics

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High-temperature operation of metal-semiconductor-metal (MSM) UV photodetectors fabricated on pulsed laser deposited β-Ga2O3 thin films has been investigated. These photodetectors were operated up to 250 °C temperature under 255 nm illumination. The photo current to dark current (PDCR) ratio of about 7100 was observed at room temperature (RT) while it had a value 2.3 at 250 °C at 10 V applied bias. A decline in photocurrent was observed from RT to 150 °C and then it increased with temperature up to 250 °C. The suppression of the blue band was also observed from 150 °C temperature which indicated that self-trapped holes in Ga2O3 became unstable. Temperature-dependent rise and decay times of carriers were analyzed to understand the photocurrent mechanism and persistence photocurrent at high temperatures. Coupled electron-phonon interaction with holes was found to influence the photoresponse in the devices. The obtained results are encouraging and significant for high-temperature applications of β-Ga2O3 MSM deep UV photodetectors.

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“…Remarkably, Δϕ ox matches the quantity

{(ϕ_{B}^{eff, AIR} - ϕ_{B}^{eff, UHV})}_{Au} = 0.48 eV

we measured for evaporated Au SBD stored in air/UHV, respectively, which greatly supports previous arguments. Measurements by Kelvin probe force microscopy on β‐Ga 2 O 3 thin films further confirm that point defects can modulate the work function of β‐Ga 2 O 3 by as much as ≈0.4 eV 43. Following this picture, the metal/β‐Ga 2 O 3 interface appears dominated by an ubiquitous inhomogeneous interfacial layer that assists interfacial oxygen incorporation (excorporation) in air (vacuum).…”

Section: Resultsmentioning

confidence: 77%

Benchmarking β‐Ga₂O₃ Schottky Diodes by Nanoscale Ballistic Electron Emission Microscopy

Buzio

Gerbi

et al. 2020

Adv Elect Materials

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Monoclinic beta‐phase gallium oxide (β‐Ga2O3) is an ultrawide‐bandgap semiconductor, intensively studied as a viable candidate for next‐generation power electronics, optoelectronics, and extreme environment electronics. Schottky contacts to β‐Ga2O3 are of paramount importance to this end; however, they are not yet fundamentally understood. Intrinsic sources of interfacial disorder, including oxygen‐related defects and extrinsic fabrication factors, are thought to greatly determine the properties of such contacts, for example by originating Fermi level pinning and causing patches with different Schottky barrier heights (SBHs). Ballistic electron emission microscopy (BEEM) is used to probe band bending and interfacial inhomogeneity at the nanoscale for prototypical Au/ and Pt/(100)β‐Ga2O3 single crystal Schottky barrier diodes. It is shown that SBH fluctuations amount to 40–60 meV under vacuum, occurring over length scales of tens of nanometers. Furthermore, a remarkable SBH modulation of ≈0.2 eV takes place upon exposure of devices from vacuum to ambient air. Such findings—better obtained by BEEM than by macroscale approaches—point to the existence of an ubiquitous inhomogeneous interfacial layer, controlling band bending and ambient sensitivity via oxygen ionosorption and interface redox chemistry. This study ascribes a key role to interfacial oxygen vacancies, and has practical implications for transport modelling and interface engineering.

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Point defects induced work function modulation of β-Ga2O3

Cited by 89 publications

References 24 publications

Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

High-temperature photocurrent mechanism of β-Ga2O3 based metal-semiconductor-metal solar-blind photodetectors

Benchmarking β‐Ga₂O₃ Schottky Diodes by Nanoscale Ballistic Electron Emission Microscopy

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Point defects induced work function modulation of β-Ga2O3

Cited by 89 publications

References 24 publications

Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

Wide range temperature-dependent (80–630 K) study of Hall effect and the Seebeck coefficient of β -Ga2O3 single crystals

High-temperature photocurrent mechanism of β-Ga2O3 based metal-semiconductor-metal solar-blind photodetectors

Benchmarking β‐Ga2O3 Schottky Diodes by Nanoscale Ballistic Electron Emission Microscopy

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Resources

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Benchmarking β‐Ga₂O₃ Schottky Diodes by Nanoscale Ballistic Electron Emission Microscopy