Microscopic Origin of Electron Accumulation in<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>In</mml:mi><mml:mn>2</mml:mn></mml:msub><mml:msub><mml:mi mathvariant="bold">O</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>

Zhang, Khl; Egdell, R.G.; Offi, Francesco; Iacobucci, S.; Petaccia, L.; Gorovikov, Sergey; King, P. D. C.

doi:10.1103/physrevlett.110.056803

Cited by 109 publications

(116 citation statements)

References 36 publications

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“…However, presence of nanocrystallites in the amorphous phase and formation of microcrystalline structure were observed as well [5,16]. So, the values of electron effective mass m* = 0.2…0.3m 0 , which was reported in the literature for polycrystalline films and single crystals [18][19][20] [21]. A similar value of 5.5·10 18 cm -3 was also obtained in [20].…”

Section: Resultssupporting

confidence: 63%

Trap-assisted conductivity in anodic oxide on InSb

Beketov¹

2017

Semicond. Phys. Quantum Electron. Optoelectron.

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Abstract. The direct current conductivity of anodic oxide of InSb has been investigated as a function of applied bias and temperature. Proposed in this work is a model of conductivity that includes ohmic, trap-assisted tunneling and Poole-Frenkel conduction processes. Two defect states were found in the energy gap of the anodic oxide, which can be attributed to bulk traps. The asymmetry in the current-voltage characteristics is analyzed in terms of comparative distribution of the applied bias voltage between the anodic oxide and the depletion region in InSb.

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Section: Resultssupporting

confidence: 63%

Trap-assisted conductivity in anodic oxide on InSb

Beketov¹

2017

Semicond. Phys. Quantum Electron. Optoelectron.

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“…Previously, several TA studies have demonstrated that, in metal oxides, oxygen vacancies and surface hydroxyl groups create midgap states that act as electron and hole traps, respectively (21,(27)(28)(29). It is generally believed that oxygen vacancies create donor states just below the CB edge, whereas surface hydroxyl groups create acceptor states just above the VB edge.…”

Section: Et Al Have Demonstrated Thatmentioning

confidence: 99%

“…surface oxygen vacancies can act as traps for excited-state electrons (27)(28)(29), whereas surface hydroxyl groups typically function as hole traps (21,27). Transient absorption (TA) spectroscopy has been used extensively to understand the processes that govern the relaxation dynamics of photoexcited electrons and holes and has been successfully applied to the study of midgap states in metal oxides (21,22,26,27,(30)(31)(32)(33)(34).…”

Section: Significancementioning

confidence: 99%

Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO ₂ reduction

Hoch

Szymanski

Ghuman

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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In 2 O 3-x (OH) y nanoparticles have been shown to function as an effective gas-phase photocatalyst for the reduction of CO 2 to CO via the reverse water-gas shift reaction. Their photocatalytic activity is strongly correlated to the number of oxygen vacancy and hydroxide defects present in the system. To better understand how such defects interact with photogenerated electrons and holes in these materials, we have studied the relaxation dynamics of In 2 O 3-x (OH) y nanoparticles with varying concentration of defects using two different excitation energies corresponding to above-band-gap (318-nm) and near-band-gap (405-nm) excitations. Our results demonstrate that defects play a significant role in the excited-state, charge relaxation pathways. Higher defect concentrations result in longer excited-state lifetimes, which are attributed to improved charge separation. This correlates well with the observed trends in the photocatalytic activity. These results are further supported by density-functional theory calculations, which confirm the positions of oxygen vacancy and hydroxide defect states within the optical band gap of indium oxide. This enhanced understanding of the role these defects play in determining the optoelectronic properties and charge carrier dynamics can provide valuable insight toward the rational development of more efficient photocatalytic materials for CO 2 reduction.indium oxide | solar fuels | CO 2 hydrogenation | transient absorption | surface defects C oncerns over climate change and the projected rise in global energy demand have motivated researchers to develop alternative, more sustainable ways to generate energy from naturally abundant and renewable sources (1-3). An important challenge associated with using renewable energy sources, such as solar, is their inherent intermittent nature (4-6). The emerging field of solar fuels seeks to address this issue by storing radiant solar energy in chemical bonds, which can then be released on demand and act as a drop-in replacement for traditional fossil fuels (7-11). By using the greenhouse gas, CO 2 , currently regarded as a waste product, as a feedstock and converting it into valuable products such as solar fuels or platform chemicals, we could simultaneously address concerns over climate change and energy security while creating significant economic benefits (12)(13)(14). However, despite recent advances in the development of active materials that can drive the photocatalytic reduction of CO 2 into useful chemical species, much remains unknown about the fundamental physical properties that control the activity of a photocatalyst. To facilitate the rational development and improvement of photocatalytic materials, a detailed understanding of the complex interplay between chemical, optical, and electronic processes is needed.Indium oxide has many favorable optical, electronic, and surface properties that make it a compelling choice as a photocatalyst for CO 2 reduction. It has a relatively high conduction band, and common defects such as oxyge...

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“…These two strategies have been found equivalent [26,29]. Nonetheless, angle-resolved photoelectron spectroscopy (ARPES) studies of the 2DEGs band structure have evidenced that the subband energies are not described well by such models [3,6,7]. It has been then proposed that taking into account many-body interactions could resolve the problem [3].…”

Section: Introductionmentioning

confidence: 99%

“…Two-dimensional electron gases (2DEGs) occurring at surfaces of semiconductors have been studied for many years due to their rich phenomenology and extreme technological relevance [1][2][3][4][5][6][7][8][9][10][11][12][13]. The 2DEGs arise following subsurface confinement of conduction electrons caused by an electric field.…”

Section: Introductionmentioning

confidence: 99%

Effect of a skin-deep surface zone on the formation of a two-dimensional electron gas at a semiconductor surface

et al. 2016

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Two-dimensional electron gases (2DEGs) at surfaces and interfaces of semiconductors are described straightforwardly with a one-dimensional (1D) self-consistent Poisson-Schrödinger scheme. However, their band energies have not been modeled correctly in this way. Using angle-resolved photoelectron spectroscopy we study the band structures of 2DEGs formed at sulfur-passivated surfaces of InAs(001) as a model system. Electronic properties of these surfaces are tuned by changing the S coverage, while keeping a high-quality interface, free of defects and with a constant doping density. In contrast to earlier studies we show that the Poisson-Schrödinger scheme predicts the 2DEG band energies correctly but it is indispensable to take into account the existence of the physical surface. The surface substantially influences the band energies beyond simple electrostatics, by setting nontrivial boundary conditions for 2DEG wave functions.

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Microscopic Origin of Electron Accumulation inIn2O3

Cited by 109 publications

References 36 publications

Trap-assisted conductivity in anodic oxide on InSb

Trap-assisted conductivity in anodic oxide on InSb

Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO ₂ reduction

Effect of a skin-deep surface zone on the formation of a two-dimensional electron gas at a semiconductor surface

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Microscopic Origin of Electron Accumulation inIn2O3

Cited by 109 publications

References 36 publications

Trap-assisted conductivity in anodic oxide on InSb

Trap-assisted conductivity in anodic oxide on InSb

Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO 2 reduction

Effect of a skin-deep surface zone on the formation of a two-dimensional electron gas at a semiconductor surface

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Product

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Carrier dynamics and the role of surface defects: Designing a photocatalyst for gas-phase CO ₂ reduction