Electronic properties of layered multicomponent wide-band-gap oxides: A combinatorial approach

Murat, Altynbek; Medvedeva, Julia E.

doi:10.1103/physrevb.85.155101

Cited by 32 publications

(23 citation statements)

References 30 publications

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“…Indeed, the Al-O bond is the strongest compared to the In-O and Zn-O bonds in InAlZnO 4 , and the oxygen vacancy defect is least likely to be formed near the Al atoms. This tendency is stronger when the Al is a planar neighbor rather than the apical one simply because the planar metal-oxygen distances are generally shorter than the apical ones in the layered InAM O 4 compounds [28].…”

Section: Formation Of Stable Fourfold Structures In Oxygen Deficiementioning

confidence: 96%

“…Because of the different ionic radii and the valence state of the cations in the AM O 2.5 double layer, the A 3+ and M 2+ atoms have different z component of the internal site position 6(c). The optimized structural parameters for every structure under consideration can be found in our previous work [28].…”

Section: Approachmentioning

confidence: 99%

“…As mentioned in the Introduction, both A and M atoms in InAM O 4 have an unusual five-fold oxygen coordination. It has been shown [28] that this unusual coordination plays a critical role in determining the electronic properties of layered multicomponent oxides such as the band gap, the electron effective mass, and the orbital composition of the conduction band. To understand how the local coordination affects the formation energy of the oxygen vacancy, we performed defect calculations for several unstable ZnO phases, namely, for zincblende (fourfold coordination), hypothetical wurtzite-based (fivefold), and rocksalt (sixfold) structures -in addition to the ground state wurtzite ZnO phase.…”

Section: A Oxygen Vacancy In Binary Oxidesmentioning

confidence: 99%

“…To understand how the local coordination affects the formation energy of the oxygen vacancy, we performed defect calculations for several unstable ZnO phases, namely, for zincblende (fourfold coordination), hypothetical wurtzite-based (fivefold), and rocksalt (sixfold) structures -in addition to the ground state wurtzite ZnO phase. For the hypothetical ZnO phase with fivefold oxygen coordination, the lattice parameters as well as the internal atomic positions were chosen so that the metal-oxygen distances are similar to the Zn-O distances in the multicomponent InGaZnO 4 oxide [28]. Using 84-atom supercells for wurtzite and hypothetical wurtzitebased structures and 128-atom supercells for zincblende and rocksalt structures of ZnO, we calculate the formation energy of an oxygen vacancy in these ZnO phases.…”

Section: A Oxygen Vacancy In Binary Oxidesmentioning

confidence: 99%

“…The little sensitivity of the mobility on the chemical composition can be explained based on the results of the electronic band structure investigations of undoped stoichiometric InAM O 4 compounds with A 3+ =Al or Ga, and M 2+ =Ca or Zn. It was shown [28] that the electronic properties of these layered-structured multicomponent oxides resemble those in the conventional binary transparent conductive oxides (TCOs): both exhibit a dispersed s-like conduction band and possess a small (0.3-0.5 m e ), isotropic electron effective mass. Strikingly, it was found that despite the different band gaps of the constituent basis binary oxides (2-4 eV In 2 O 3 or ZnO; 5 eV for Ga 2 O 3 ; and 7-9 eV in CaO or Al 2 O 3 ), the states of all cations contribute to the bottom of the conduction band of the multicomponent oxide.…”

Section: Introductionmentioning

confidence: 99%

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Composition-dependent oxygen vacancy formation in multicomponent wide-band-gap oxides

Murat

Medvedeva

2012

Phys. Rev. B

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The formation and distribution of oxygen vacancy in layered multicomponent InAM O4 oxides with A 3+ =Al or Ga, and M 2+ =Ca or Zn, and in the corresponding binary oxide constituents is investigated using first-principles density functional calculations. Comparing the calculated formation energies of the oxygen defect at six different site locations within the structurally and chemically distinct layers of InAM O4 oxides, we find that the vacancy distribution is significantly affected not only by the strength of the metal-oxygen bonding, but also by the cation's ability to adjust to anisotropic oxygen environment created by the vacancy. In particular, the tendency of Zn, Ga, and Al atoms to form stable structures with low oxygen coordination, results in nearly identical vacancy concentrations in the InO1.5 and GaZnO2.5 layers in InGaZnO4, and only an order of magnitude lower concentration in the AlZnO2.5 layer as compared to the one in the InO1.5 layer in InAlZnO4. The presence of two light metal constituents in the InAlCaO4 along with Ca failure to form a stable fourfold coordination as revealed by its negligible relaxation near the defect, leads to a strong preference of the oxygen vacancy to be in the InO1.5 layer. Based on the results obtained, we derive general rules on the role of chemical composition, local coordination, and atomic relaxation in the defect formation and propose an alternative light-metal oxide as a promising constituent of multicomponent functional materials with tunable properties.

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Section: Formation Of Stable Fourfold Structures In Oxygen Deficiementioning

confidence: 96%

Section: Approachmentioning

confidence: 99%

Section: A Oxygen Vacancy In Binary Oxidesmentioning

confidence: 99%

Section: A Oxygen Vacancy In Binary Oxidesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Composition-dependent oxygen vacancy formation in multicomponent wide-band-gap oxides

Murat

Medvedeva

2012

Phys. Rev. B

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Determination of the Band Alignment of a‐IGZO/a‐IGMO Heterojunction for High‐Electron Mobility Transistor Application

Zhang

Liu

2017

Physica Rapid Research Ltrs

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In the past decade, amorphous InGaZnO thin film transistors (a-IGZO TFTs) have become a very promising candidate for application in flat panel displays (FPDs). However, it is difficult to break through the mobility bottleneck of a-IGZO TFTs to obtain mobilities higher than 100 cm 2 V À1 s À1 , thus limiting their use in more advanced applications. Construction of a high-electron mobility transistor (HEMT) based on a heterojunction structure could provide a solution for this problem. In this work, the band alignment of a-IGZO and amorphous InGaMgO (a-IGMO) heterojunction has been investigated using X-ray photoelectron spectroscopy (XPS) and transmission spectra measurements. The valence band (DE V ) and conduction band offsets (DE C ) were determined as 0.09 and 0.83 eV, respectively. The DE C was large enough to construct a potential well that could favor the appearance of a twodimensional electron gas (2DEG). Hence, the achievement of an HEMT based on a-IGZO/a-IGMO heterojunction can be expected. Moreover, band bending contributed greatly to such a large DE C , and thus to the formation of electrical confinement structure. Our findings suggest that a-IGZO/a-IGMO heterojunction is a potential candidate for constructing a HEMT and thus breaking through the mobility bottleneck of a-IGZO-based TFTs for the applications in next-generation electronic products.In the past decade, a-IGZO thin film transistors (TFTs) have proven to be one of the most promising candidates for the applications in flat panel displays (FPDs) as a result of their excellent uniformity, high transparency to visible light, and large field effect mobility (m FE , over 10 cm 2 V À1 s À1 ). [1,2] Researchers have been attempting to increase the mobility m FE of a-IGZO TFTs in order to realize displays with higher resolution, faster frame rate, and larger panel size. For instance, Wu et al. [3] obtained an a-IGZO TFT with a m FE of 33.5 cm 2 V À1 s À1 by using an atmospheric-pressure-plasma-treated SiO 2 gate dielectric. The a-IGZO TFT with HfLaO gate dielectric was treated in a CHF 3 /O 2 plasma, thus increasing the m FE to an ultrahigh value of 39.8 cm 2 V À1 s À1 . [4] Recently, Zheng et al. [5] reported a highmobility a-IGZO TFT (m FE > 60 cm 2 V À1 s À1 ) with an atomic-layer-deposited SiO 2 gate insulator. Nevertheless, the m FE of a-IGZO TFTs is still not high enough, especially for satisfying some more advanced applications such as 3D displays, flexible logic circuits, and system-on-panel devices. [1] According to previous studies, an extremely high carrier mobility can be realized in the HEMT based on a heterojunction structure due to the space separation of the two-dimensional electron gas (2DEG) and ionized donors. For instance, the AlGaN/GaN heterojunction that was widely adopted to form HEMTs can yield a 2DEG, thus increasing the electron mobility to over 1500 cm 2 V À1 s À1 . [6] A ZnMgO/ZnO heterojunction reveals the potential for a high-frequency and high-power HEMT application due to the large 2DEG-induced mobility of 250 cm 2

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Design, Properties, and TFT Application of Solution‐Processed In‐Ga‐Cd‐O Thin Films

Song

Javaid

Liang

et al. 2018

Physica Rapid Research Ltrs

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Concerning the revolutionary future of electronic devices, high‐performance solution‐processable semiconductors have earned increasing academic and industrial research interests. In this paper, we synthesize In‐Ga‐Cd‐O semiconductor thin films via a solution method. Transparent amorphous/nanocrystalline oxide thin films with small surface roughness have been grown by controlling the relative ratio of Cd‐content. The present thin‐film transistor with an optimized Cd‐ratio exhibits a saturation field‐effect mobility up to 10 cm2 V−1 s−1, an on/off current ratio of ≈1.3 × 109, and a threshold voltage shift of ≈2.6 V under −5 V gate bias of 10 000 s, which are superior or comparable to those reported values of solution‐processed conventional In‐Ga‐Zn‐O counterparts. Our results indicate that the proposed In‐Ga‐Cd‐O semiconductor would endow a promising transparent amorphous/nanocrystalline active material for electronic devices.

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Electronic properties of layered multicomponent wide-band-gap oxides: A combinatorial approach

Cited by 32 publications

References 30 publications

Composition-dependent oxygen vacancy formation in multicomponent wide-band-gap oxides

Composition-dependent oxygen vacancy formation in multicomponent wide-band-gap oxides

Determination of the Band Alignment of a‐IGZO/a‐IGMO Heterojunction for High‐Electron Mobility Transistor Application

Design, Properties, and TFT Application of Solution‐Processed In‐Ga‐Cd‐O Thin Films

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