Sensor effect theory for the detection of reducing gases

Kozhushner, M. A.; Bodneva, V. L.; Трахтенберг, Л. И.

doi:10.1134/s0036024412080055

Cited by 13 publications

(7 citation statements)

References 10 publications

(30 reference statements)

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“…Although the electron binding energy ε d of a single oxygen vacancy donor is unknown, the estimate of ε d can be obtained by using the experimental temperature dependence of the conductivity of a bulk sample of In 2 O 3 measured in refs and . This is because the conductivity of the semiconductor is approximately proportional to the concentration of conduction electrons n c ∼ exp{−ε d /2 kT }. , The estimates based on the conductivity of bulk In 2 O 3 give ε d ≈ 0.2 eV, which is approximately the same as the value obtained using conductivity measurements for the nanostructured In 2 O 3 film sample in vacuum, i.e. upon removal of the oxygen adsorbates .…”

Section: Equilibrium Distribution Of the Charges Inside Spherical Nan...mentioning

confidence: 61%

“…This is because the conductivity of the semiconductor is approximately proportional to the concentration of conduction electrons n c ∼ exp{−ε d /2kT}. 15,16 The estimates based on the conductivity of bulk In 2 O 3 give ε d ≈ 0.2 eV, which is approximately the same as the value obtained using conductivity measurements for the nanostructured In 2 O 3 film sample in vacuum, i.e. upon removal of the oxygen adsorbates.…”

Section: Inside Spherical Nanoparticlesmentioning

confidence: 92%

“…On the other hand, the conductivity within the nanoparticle system depends mainly on the concentration of conduction electrons at the surface. In addition, the sensor effect  the change in conductivity of the semiconductor nanoparticle thin film upon introduction of various environmental gases ,−  is also determined by the spatial distribution of charge carriers. Therefore, the quantitative description of the sensor effect requires knowledge of the concentration of the conduction electrons near the nanoparticle’s surface and its dependence on the concentration of the surface adsorbates.…”

Section: Introductionmentioning

confidence: 99%

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Inhomogeneous Charge Distribution in Semiconductor Nanoparticles

et al. 2015

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The inhomogeneous spatial distribution of charge carriers within semiconductor oxide nanoparticles is investigated by taking into account processes involving the interaction of conduction electrons with oxygen donor vacancies in the bulk and with oxygen adsorbates at the surface. The main characteristics of the semiconductor nanoparticles, such as the surface charge, the distributions of positive and negative charges in the bulk, and the temperature dependence of the concentration of conduction electrons, are determined selfconsistently by taking into account the interaction of all charges in the system under conditions of complete thermodynamic equilibrium. The developed statistical mechanics model allows us to determine the net surface negative charge on oxygen atoms, the spatial distributions of the conduction electrons, the positively charged ionized donors, and the electrical potential inside the nanoparticle as a function of nanoparticle radius and temperature.

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Section: Equilibrium Distribution Of the Charges Inside Spherical Nan...mentioning

confidence: 61%

Section: Inside Spherical Nanoparticlesmentioning

confidence: 92%

Section: Introductionmentioning

confidence: 99%

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Inhomogeneous Charge Distribution in Semiconductor Nanoparticles

et al. 2015

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“…For a quantitative description of the observed processes, mathematical models, presented in other studies [34][35][36]49,50] for β-Ga 2 O 3 layers and other metal oxide semiconductors under the condition L D ≥ D g /2, can be applied.…”

Section: Gas-sensing Mechanismmentioning

confidence: 99%

“…In contrast, if the condition L D > D g /2 is maintained, an increase in the electron concentration in the semiconductor should lead to an increase in the density of chemisorbed oxygen and the response to reducing gases at lower temperatures, which was confirmed experimentally. [50] In addition, the introduced additives of metals can significantly change the microstructure of the surface of the Ga 2 O 3 layers, leading to an increase in the specific surface area and the response to gases, as well as acting as additional adsorption centers with high catalytic activity. [23,51] Additional researches are needed for a more detailed study of the effect of tin additive on the gas-sensitive properties of the ε-Ga 2 O 3 layers.…”

Section: Gas-sensing Mechanismmentioning

confidence: 99%

Gas Sensors Based on Pseudohexagonal Phase of Gallium Oxide

Аlmaev

Николаев

Butenko

et al. 2021

Physica Status Solidi (b)

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Gallium oxide Ga 2 O 3 has at least five known polymorphic forms commonly denoted as α, β, γ, δ, and ε(κ). [1] According to recent findings, ε-Ga 2 O 3 is not a true polymorph of hexagonal P6 3 mc symmetry; rather, it is composed of twinned rotational domains of orthorhombic κ-Ga 2 O 3 of Pna2 1 space group. [2] All Ga 2 O 3 polymorphs are ultrawide-bandgap semiconductors and are promising for applications in power and sensor electronics. There is growing interest in the research of metastable polymorphs, including the pseudohexagonal ε-Ga 2 O 3 form.Pseudohexagonal ε-Ga 2 O 3 is stable up to the temperature of T ¼ 700 C and is epitaxially compatible with other semiconducting materials with a hexagonal or pseudohexagonal structure such as AlN, GaN, 6H-SiC, sapphire, and some other metal oxides. [3,4] The reported bandgap energy of ε-Ga 2 O 3 is close to that of β-Ga 2 O 3 and varies from 4.5 to 5.0 eV. [5][6][7][8][9] The ε-Ga 2 O 3 phase exhibits ferroelectric properties, [3,6,10,11] enabling the development of high-electron-mobility transistors (HEMTs) based on this material. [12] Solar-blind UV detectors based on ε-Ga 2 O 3 demonstrate record characteristics [5,[13][14][15][16] due to the high symmetry of this polymorph.Previously, we studied the effect of H 2 on the electrical conductivity and gas-sensing properties of the Pt-contacted doublephase ε-Ga 2 O 3 /α-Ga 2 O 3 :Sn structures grown by halide vaporphase epitaxy (HVPE) on patterned sapphire substrates (PSS). [17] These structures showed response to H 2 starting from room temperature (RT). The minimum detectable H 2 concentration was 54 ppm at T ¼ 125 C. At low applied voltages U < 7.5 V, the double-phase structures showed no response to CH 4 , O 2 , CO, and NH 3 . At U ¼ 7.5-150 V, these structures showed a significant response to O 2 and NH 3 . The authors concluded that the H 2 sensitivity of Pt-contacted double-phase α-Ga 2 O 3 /ε-Ga 2 O 3 structures was caused by the change of the energy barrier height at the interface between the catalytically active Pt contact and ε-Ga 2 O 3 . The reduction of Sn impurity concentration in ε-Ga 2 O 3 / α-Ga 2 O 3 from %4 Â 10 18 to %1.5 Â 10 17 cm À3 led to increase in sensitivity to O 2 at T ¼ 180-220 C and U ≤ 7.5 V. [18] The exposure to oxygen caused a reversible decrease in the current I through the structure. The gas-sensing effect was manifested in modulation of I due to the chemisorption of O 2 on the

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