Origin of Enhanced Electromechanical Coupling in (Yb,Al)N Nitride Alloys

Jia, Junjun; Yanagitani, Takahiko

doi:10.1103/physrevapplied.16.044009

Cited by 15 publications

(47 citation statements)

References 31 publications

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“…For most AlN-based nitride alloys, such substitution often causes 1) an increase in field-induced strain via an increase in the longitudinal piezoelectric constant e 33 and (2) a simultaneous decrease in the longitudinal elastic stiffness c 33 . 1,5,6 The same tendency is a) Electronic mail: jia@aoni.waseda.jp b) Electronic mail: yanagitani@waseda.jp seen in GaN, but the k 2 t in GaN-based nitride alloys is difficult to reach that of AlN alloys. Is such a difference an intrinsic feature for GaN or does it come from experimental fabrication conditions?…”

Section: Introductionmentioning

confidence: 80%

“…Our sputtering experiments have demonstrated that Yb alloying concentration is much higher in GaN than one in AlN; 2 k 2 t disappears above 25% YbN in the sputtered (Yb,Al)N films, and such disappearance occurs above 32% YbN in the sputtered (Yb,Ga)N films. 2 Surprisingly, although GaN alloy can reach higher alloy concentration, (Yb,Ga)N alloy only has a maximal k 2 t value of 3.2%, 2 which is obviously lower than that of (Yb, Al)N. 1 The difference in k 2 t between them may come from the difference between d and s orbits, becasue Al has a [Ne]3s 2 3p 1 configuration, different from [Ar]4s 2 3d 10 4p 1 of Ga from the perspective of electronic structure. In this paper, we will show that although the calculations with the semicore d electrons reproduces the expeiments well, such treatment cannot explain the difference in k 2 t between Yb-substituted AlN and GaN alloys.…”

Section: Introductionmentioning

confidence: 97%

“…Group-III nitride material AlN is currently used widely in various microwave communication applications, such as GHz frequency filters in 5G applications, because of their high thermal stability, operating frequencies, Q factor, and reliability. 1,2 For these applications, the small electromechanical coupling coefficient (k 2 t ) of AlN can be enhanced by alloying with rocksalt nitrides such as ScN, YN, or YbN. [2][3][4][5][6] As an alternative III-V semiconductor, GaN shows a promising temperature coefficient of frequency (-12.6 ppm/ • C), 2,7 which is lower than that of AlN, and advantageous for application of frequencystable resonators.…”

Section: Introductionmentioning

confidence: 99%

“…[2][3][4][5][6] As an alternative III-V semiconductor, GaN shows a promising temperature coefficient of frequency (-12.6 ppm/ • C), 2,7 which is lower than that of AlN, and advantageous for application of frequencystable resonators. However, GaN nitride alloy shows a relatively small k 2 t , about one-third of AlN nitride alloy, 1,2 which limits the resonator applications because the bandwidth and the filter insertion loss is determined by the k 2 t value of the piezoelectric layer. It is therefore necessary to have a systematic theoretical and experimental investigation on the k 2 t enhancement in GaN alloy.…”

Section: Introductionmentioning

confidence: 99%

“…Following the above enhancement mechanism, a large k 2 t often requires high alloy concentrations, e.g., 42% ScN or 11% YbN in the AlN films, 1,3 and thus a high concentration substitution, making it difficult to produce alloy films under equilibrium conditions. In practice, nonequilibrium physical vapor deposition techniques, such as sputtering, are widely employed to fabricate disordered solid solutions.…”

Section: Introductionmentioning

confidence: 99%

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Electromechanical coupling in Yb-substituted III-V nitride alloys

Jia¹,

Iwata²,

Suzuki³

et al. 2022

Preprint

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Yb-substitution induced enhancement for electromechanical coupling in wurtzite III-V nitrides is studied via theoretical calculations and experiments. The substitution induced local strain and mechanical softening enhanced electromechanical coupling. Interestingly, mechanical softening induced by Yb substitution shows less dependence on the parent AlN and GaN, which is considered to originate from the Yb-Yb pair interaction. The difference in enhancement of electromechanical coupling for the alloys mainly comes from the enhanced piezoelectric response. Spontaneous polarization induced by the strain plays a key role in enhancing the piezoelectric response, which can be improved by selecting the wurtzite structure with an optimized internal parameter. Additionally, when the substitutional element has significantly different ionic size from the host cation, the piezoelectric response due to the internal strain is considerably enhanced. This can serve as a simple guideline to identify alloying components in a search for a massive increase in electromechanical coupling.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Electromechanical coupling in Yb-substituted III-V nitride alloys

Jia¹,

Iwata²,

Suzuki³

et al. 2022

Preprint

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Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Zha,

Luo,

Tao

et al. 2024

AAPPS Bull.

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Bandpass filters with high frequency and wide bandwidth are indispensable parts of the fifth-generation telecommunication technologies, and currently, they are mainly based on surface and bulk acoustic wave resonators. Owing to its high mechanical strength, excellent stability at elevated temperatures, good thermal conductivity, and compatibility with complementary metal-oxide-semiconductor technology, aluminum nitride (AlN) becomes the primary piezoelectric material for high-frequency resonators. This review briefly introduces the structures and key performance parameters of the acoustic resonators. The common filter topologies are also discussed. In particular, research progresses in the piezoelectric AlN layer, electrodes, and substrates of the resonators are elaborated. Increasing the electromechanical coupling constant is the main concern for the AlN film. To synthesize AlN in single-crystalline or poly-crystalline with a high intensity of (0002) orientation, and alloy the AlN with other elements are two effective approaches. For the substrates and bottom electrodes, lattice and thermal expansion mismatch, and surface roughness are critical for the synthesis of a high-crystal-quality piezoelectric layer. The electrodes with low electrical resistance, large acoustic-impedance mismatch to the piezoelectric layer, and low density are ideal to reduce insertion loss. Based on the research progress, several possible research directions in the AlN-based filters are suggested at the end of the paper.

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Synthesis and Calculations of Wurtzite Al_1–xGd_xN Heterostructural Alloys

et al. 2022

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Al1–x Gd x N is one of a series of novel heterostructural alloys involving rare earth cations with potentially interesting properties for (opto)electronic, magnetic, and neutron detector applications. Using alloy models in conjunction with density functional theory, we explored the full composition range for Al1–x Gd x N and found that wurtzite is the ground-state structure up to a critical composition of x c = 0.82. The calculated temperature-composition phase diagram reveals a large miscibility gap inducing spinodal decomposition at equilibrium conditions, with higher Gd substitution (meta)stabilized at higher temperatures. By depositing combinatorial thin films at high effective temperatures using radio-frequency cosputtering, we have achieved the highest Gd3+ incorporation into the wurtzite phase reported to date, with single-phase compositions at least up to x ≈ 0.25 confirmed by high-resolution synchrotron grazing incidence wide-angle X-ray scattering. High-resolution transmission electron microscopy on material with x ≈ 0.13 and x ≈ 0.24 confirmed a uniform composition polycrystalline film with uniform columnar grains having the wurtzite structure. Spectroscopic ellipsometry and cathodoluminescence spectroscopy measurements are employed to probe the optoelectronic properties, showing that the band gap decreases with increasing Gd content x and that this effect causes the ideal Gd substitution level for cathodoluminescence applications to be low. Expanding our calculations to other rare earth cations (Pr3+ and Tb3+) reveals similar thermodynamic stability and solubility behavior to Gd. From this and previous studies on Al1–x Sc x N, we elucidate that both smaller ionic radius and higher bond ionicity promote increased incorporation of group IIIB cations into wurtzite AlN. This work furthers the development of design rules for new alloys in this material family.

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Origin of Enhanced Electromechanical Coupling in (Yb,Al)N Nitride Alloys

Cited by 15 publications

References 31 publications

Electromechanical coupling in Yb-substituted III-V nitride alloys

Electromechanical coupling in Yb-substituted III-V nitride alloys

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Synthesis and Calculations of Wurtzite Al_1–xGd_xN Heterostructural Alloys

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Origin of Enhanced Electromechanical Coupling in (Yb,Al)N Nitride Alloys

Cited by 15 publications

References 31 publications

Electromechanical coupling in Yb-substituted III-V nitride alloys

Electromechanical coupling in Yb-substituted III-V nitride alloys

Surface and bulk acoustic wave resonators based on aluminum nitride for bandpass filters

Synthesis and Calculations of Wurtzite Al1–xGdxN Heterostructural Alloys

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Product

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Synthesis and Calculations of Wurtzite Al_1–xGd_xN Heterostructural Alloys