Ab initio study on the adsorption mechanism of oxygen on Cr2AlC (0 0 0 1) surface

Li, Neng; Sakidja, Ridwan; Ching, W. Y.

doi:10.1016/j.apsusc.2014.07.065

Cited by 16 publications

(4 citation statements)

References 66 publications

(75 reference statements)

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“…Computational simulations on the IL growth mechanisms and its effect on ALD growth were carried out using density functional theory calculations using the nudged-elastic band method and AIMD simulations under constant temperature and volume with 1 fs for each trajectory step as implemented in VASP and Quantum Espresso codes. Detailed procedures to model the Al surface reactions can be found in our previous works. − …”

Section: Methodsmentioning

confidence: 99%

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

Wilt

Sakidja

Goul

et al. 2017

ACS Appl. Mater. Interfaces

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Electron tunneling through high-quality, atomically thin dielectric films can provide a critical enabling technology for future microelectronics, bringing enhanced quantum coherent transport, fast speed, small size, and high energy efficiency. A fundamental challenge is in controlling the interface between the dielectric and device electrodes. An interfacial layer (IL) will contain defects and introduce defects in the dielectric film grown atop, preventing electron tunneling through the formation of shorts. In this work, we present the first systematic investigation of the IL in AlO dielectric films of 1-6 Å's in thickness on an Al electrode. We integrated several advanced approaches: molecular dynamics to simulate IL formation, in situ high vacuum sputtering atomic layer deposition (ALD) to synthesize AlO on Al films, and in situ ultrahigh vacuum scanning tunneling spectroscopy to probe the electron tunneling through the AlO. The IL had a profound effect on electron tunneling. We observed a reduced tunnel barrier height and soft-type dielectric breakdown which indicate that defects are present in both the IL and in the AlO. The IL forms primarily due to exposure of the Al to trace O and/or HO during the pre-ALD heating step of fabrication. As the IL was systematically reduced, by controlling the pre-ALD sample heating, we observed an increase of the ALD AlO barrier height from 0.9 to 1.5 eV along with a transition from soft to hard dielectric breakdown. This work represents a key step toward the realization of high-quality, atomically thin dielectrics with electron tunneling for the next generation of microelectronics.

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Section: Methodsmentioning

confidence: 99%

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

Wilt

Sakidja

Goul

et al. 2017

ACS Appl. Mater. Interfaces

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“…We performed electronic structure calculations as implemented in the density functional theory approximation (VASP ab initio code) to assess the energetics of the adsorption of butane onto the oxygen‐terminating surface at the ground state (at 0 K). Further details of the method, exchange‐correlation potentials used (PAW‐PBE), and convergence criteria (electronic convergence criterion of 10 −5 eV and force convergence limit of 10 −2 eV/A) are given elsewhere . A list of chemical reactions along with the final atomic configurations are given in the Supporting Information, Table S3.…”

Section: Figurementioning

confidence: 99%

The Ti₃AlC₂ MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n‐Butane

Gnanakumar

Batyrev

et al. 2018

Angewandte Chemie

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Dehydrogenation or oxidative dehydrogenation (ODH) of alkanes to produce alkenes directly from natural gas/shale gas is gaining in importance.Ti 3 AlC 2 ,aMAX phase, which hitherto had not been used in catalysis,e fficiently catalyzest he ODH of n-butane to butenes and butadiene, which are important intermediates for the synthesis of polymers and other compounds.The catalyst, which combines both metallic and ceramic properties,i ss table for at least 30 ho n stream, even at lowO 2 :butane ratios,w ithout suffering from coking.T his material has neither lattice oxygens nor noble metals,y et au nique combination of numerous defects and at hin surface Ti 1Ày Al y O 2Ày/2 layer that is rich in oxygen vacancies makes it an active catalyst. Given the large number of compositions available,MAX phases may find applications in several heterogeneously catalyzedreactions. MAXphases,atermcoinedinthelate1990s,areafamilyofternary carbides and nitrides with layered hexagonal crystal structures.T heir name reflects their chemical formula: M n+1 AX n ,w here Mi sa ne arly transition metal, Ai sa n element (mostly from Groups 13 and 14), Xiscarbon and/or nitrogen, and n = 1, 2, or 3( see Figure 1). Most of these phases were discovered in powder form already in the 1960s, though the synthesis of phase-pure bulk samples was only achieved in 1996.[1] TheMAX phases are interesting because they exhibit au nique combination of ceramic and metallic properties.[2-4] Their bonding is acombination of covalent and metallic.[5] Thed ensity of states at the Fermi level is substantial and dominated by the d-d orbitals of the Melement.[5] Similarly,their electrical resistivity is metal-like in that it drops linearly with decreasing temperatures.T hey conduct heat and electricity like metals,y et they are elastically stiff,s trong,b rittle,a nd some are heat-tolerant like ceramics. [6] Numerous studies have been published on the electrical, thermal and mechanical properties of the MAX phases. [7][8][9][10][11][12] However,t othe best of our knowledge,n oc atalytic applications have been reported so far. Considering the combination of metallic and ceramic properties and high stability,w e anticipated that these materials could be good catalysts. Moreover,t he fact that they differ from most conventional

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“…The surface energy, adsorption energy, bonding character, and electronic structure of Cr 2 AlC (0001) surface with or without single O atom and molecular O 2 were investigated by the DFT calculations. The result showed that the O strongly bonded to the Al atom on the surface [15]. In addition, we have previously studied carbon dioxide adsorption process on La 2 Zr 2 O 7 surface using nano-scale slab models [16].…”

Section: Introductionmentioning

confidence: 99%

First principles study of nanoscale mechanism of oxygen adsorption on lanthanum zirconate surfaces

Guo

Zhang

et al. 2016

Physica E: Low-dimensional Systems and Nanostructures

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Lanthanum zirconate (La 2 Zr 2 O 7) is a rare-earth pyrochlore material, which has been proposed as a promising thermal barrier coating (TBC) material due to its low thermal conductivity and high temperature phase stability. At elevated temperatures, degradation of La 2 Zr 2 O 7 may occur due to adsorption of oxygen (O 2) on La 2 Zr 2 O 7 surfaces. This paper investigates nanoscale mechanism of O 2 adsorption on La 2 Zr 2 O 7 coating surfaces using the density functional theory (DFT) calculations. La 2 Zr 2 O 7 surface energies on (001), (011) and (111) planes are calculated. The surface free energy of (011) plane is lower than those of (001) and (111) planes. On (001), (011) and (111) planes of La 2 Zr 2 O 7 , the lowest adsorption energy occurs at 4-fold site, bridge site, and 3-fold-FCC site, respectively. Among all calculated cases, the lowest adsorption energy site is 3-fold-FCC on (111) plane, which is confirmed by the Bader charge transfer analyses. Charge density difference analyses show that the 3-fold-FCC site on (111) surface has the largest charge density, suggesting the strongest interaction between O 2 and La 2 Zr 2 O 7 surface.

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Ab initio study on the adsorption mechanism of oxygen on Cr2AlC (0 0 0 1) surface

Cited by 16 publications

References 66 publications

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

The Ti₃AlC₂ MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n‐Butane

First principles study of nanoscale mechanism of oxygen adsorption on lanthanum zirconate surfaces

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Ab initio study on the adsorption mechanism of oxygen on Cr2AlC (0 0 0 1) surface

Cited by 16 publications

References 66 publications

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al2O3 Tunnel Barriers

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al2O3 Tunnel Barriers

The Ti3AlC2 MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n‐Butane

First principles study of nanoscale mechanism of oxygen adsorption on lanthanum zirconate surfaces

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Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

Effect of an Interfacial Layer on Electron Tunneling through Atomically Thin Al₂O₃ Tunnel Barriers

The Ti₃AlC₂ MAX Phase as an Efficient Catalyst for Oxidative Dehydrogenation of n‐Butane