ScGaN and ScAlN: emerging nitride materials

Moram, M. A.; Zhang, S.

doi:10.1039/c3ta14189f

Cited by 118 publications

(62 citation statements)

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“…Consequently, there is considerable motivation to find alternative wide band gap semiconductors for use in UV optoelectronics, which have different electronic structures and different relationships between their lattice parameters and direct band gaps. Alloying GaN with ScN offers interesting possibilities in this regard 4 .…”

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confidence: 99%

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Band gaps of wurtzite ScxGa1−xN alloys

Tsui

Goff

Rhode

et al. 2015

Applied Physics Letters

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Optical transmittance measurements on epitaxial, phase-pure, wurtzite-structure Sc x Ga 1-x N films with 0 ≤ x ≤ 0.26 showed that their direct optical band gaps increased from 3.33 eV to 3.89 eV with increasing x, in agreement with theory. These films contained I 1 -and I 2 -type stacking faults. However, the direct optical band gaps decreased from 3.37 eV to 3.26 eV for Sc x Ga 1-x N films which additionally contained nanoscale lamellar inclusions of the zincblende phase, as revealed by aberration-corrected scanning transmission electron microscopy. Therefore we conclude that the apparent reduction in Sc x Ga 1-x N band gaps with increasing x is an artefact resulting from the presence of nanoscale zinc-blende inclusions.

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confidence: 99%

“…Film compositions were determined using Rutherford backscattering (RBS). RBS measurements were performed using a beam of 4 He at 2 MeV with an incidence angle of 0º. A standard detector was placed at 140º and two pin-diode detectors located symmetrically to each other at 165º.…”

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Band gaps of wurtzite ScxGa1−xN alloys

Tsui

Goff

Rhode

et al. 2015

Applied Physics Letters

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“…The combinations which show the greatest improvement, and a reason behind their success is presented in Paper II. Although most of the research into the piezoelectric nitrides is currently focused on ScAlN, attention is starting to spread to the neighboring nitrides [15][16][17]. Alloying TiN with AlN, has been found to improve both hardness [20][21][22][23][24][25] and oxidation resistance [26][27][28][29] of the film.…”

Section: Hard Coatingsmentioning

confidence: 99%

“…This means that if two clusters differ by at least one site, then the function equals to 0, and 1 if they are the same. This means that any function of the configuration 17) can be expanded in this basis set. The expansion coefficient in this equation are purely the projections…”

Section: Special Quasi-random Structure Modelmentioning

confidence: 99%

A Theoretical Study of Piezoelectricity, Phase Stability, and Surface Diffusion in Disordered Multicomponent Nitrides

Tholander¹

2014

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Disordered multicomponent nitride thin film can be used for various applications. The focus of this Licentiate Thesis lies on the theoretical study of piezoelectric properties, phase stability and surface diffusion in multifunctional hard coating nitrides using density functional theory (DFT).Piezoelectric thin films show great promise for microelectromechanical systems (MEMS), such as surface acoustic wave resonators or energy harvesters. One of the main benefits of nitride based piezoelectric devices is the much higher thermal stability compared to the commonly used lead zirconate titanate (PZT) based materials. This makes the nitride based material more suitable for application in, e.g., jet engines.The discovery that alloying AlN with ScN can increase the piezoelectric response more than 500% due to a phase competition between the wurtzite phase in AlN and the hexagonal phase in ScN, provides a fundamental basis for constructing highly responsive piezoelectric thin films. This approach was utilized on the neighboring nitride binaries, where ScN or YN was alloyed with AlN, GaN, or InN. It established the general role of volume matching the binaries to easily achieve a structural instability in order to obtain a maximum increase of the piezoelectric response. For Sc 0.5 Ga 0.5 N this increase is more than 900%, compared to GaN. Y 1−x In x N is, however, the most promising alloy with the highest resulting piezoelectric response seconded only by Sc 0.5 Al 0.5 N.Phase stability and lattice parameters (stress-strain states) of the Y 1−x Al x N alloy have been calculated in combination with experimental synthesis.Hard protective coatings based on nitride thin films have been used in industrial applications for a long time. Two of the most successful coatings are TiN and the metastable Ti 1−x Al x N. Although these two materials have been extensively investigated both experimentally and theoretically, at the atomic level little is known about Ti 1−x Al x N diffusion properties. This is in large part due to problems with configurational disorder in the alloy, because Ti and Al atoms are placed randomly at cation positions in the lattice, considerably increasing the complexity of the problem. To deal with this issues, we have used special quasi-random structure (SQS) models, as well as studying dilute concentrations of Al.One of the most important mechanisms related to the growth of Ti 1−x Al x N is surface diffusion. Because Ti 1−x Al x N is a metastable material it has to be grown iii iv as a thin film with methods such as physical vapor deposition (PVD), in which surface diffusion plays a pivotal role in determining the microstructure evolution of the film.In this work, the surface energetics and mobility of Ti and Al adatoms on a disordered Ti 0.5 Al 0.5 N(0 0 1) surface are studied. Also the effects on the adatom energetics of Ti, Al, and N by the substitution of one Ti with an Al surface atom in TiN(0 0 1), TiN(0 1 1), and TiN(1 1 1) surfaces is studied. This provides an indepth atomistic understanding o...

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“…Challenges include the difficulty of ptype doping, alongside the relatively large lattice mismatches between layers within these devices which lead to problems with internal stresses and dislocation generation [4]. Therefore, alternative materials with wide, direct, band gaps but different lattice parameters, such as Sc-based III-nitride alloys, are of interest for improving device performance [5][6][7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%

Composition measurement of epitaxial Sc_xGa_1−xN films

Tsui

Goff

Barradas

et al. 2016

Semicond. Sci. Technol.

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Four different methods for measuring the compositions of epitaxial Sc x Ga 1-x N films were assessed and compared to determine which was the most reliable and accurate. The compositions of epitaxial Sc x Ga 1-x N films with 0 ≤ x ≤ 0.26 were measured directly using Rutherford backscattering (RBS) and X-ray photoelectron spectroscopy (XPS), and indirectly using c lattice parameter measurements from X-ray diffraction and c/a ratio measurements from electron diffraction patterns. RBS measurements were taken as a standard reference. XPS was found to underestimate the Sc content, whereas c lattice parameter and c/a ratio were not reliable for composition determination due to the unknown degree of strain relaxation in the film. However, the Sc flux used during growth was found to relate linearly with x and could be used to estimate the Sc content.

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ScGaN and ScAlN: emerging nitride materials

Abstract: ScAlN and ScGaN alloys are wide band-gap semiconductors which can greatly expand the options for band gap and polarisation engineering required for efficient III-nitride optoelectronic devices, high-electron mobility transistors and energy-harvesting devices.

Cited by 118 publications

References 93 publications

Band gaps of wurtzite ScxGa1−xN alloys

Band gaps of wurtzite ScxGa1−xN alloys

A Theoretical Study of Piezoelectricity, Phase Stability, and Surface Diffusion in Disordered Multicomponent Nitrides

Composition measurement of epitaxial Sc_xGa_1−xN films

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ScGaN and ScAlN: emerging nitride materials

Abstract: ScAlN and ScGaN alloys are wide band-gap semiconductors which can greatly expand the options for band gap and polarisation engineering required for efficient III-nitride optoelectronic devices, high-electron mobility transistors and energy-harvesting devices.

Cited by 118 publications

References 93 publications

Band gaps of wurtzite ScxGa1−xN alloys

Band gaps of wurtzite ScxGa1−xN alloys

A Theoretical Study of Piezoelectricity, Phase Stability, and Surface Diffusion in Disordered Multicomponent Nitrides

Composition measurement of epitaxial ScxGa1−xN films

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Product

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Composition measurement of epitaxial Sc_xGa_1−xN films