Significant Enhancement of Piezoelectric Response in AlN by Yb Addition

Hirata, Kyoji; Mori, Yojiro; Yamada, Hiroshi; Uehara, Masato; Anggraini, Sri Ayu; Akiyama, Morito

doi:10.3390/ma14020309

Cited by 18 publications

(22 citation statements)

References 36 publications

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“…In this case, first-principles calculations are considered to be effective for evaluating the physical properties. In previous research, we investigated the piezoelectric characteristics of YbAlN by first-principles calculations, and the calculated results agreed with the experimental results …”

Section: Introductionsupporting

confidence: 71%

“…The Born effective charges ( Z 33 ) of Al (orange line) and Yb (green line) are plotted against the Yb concentration in Figure b. The average of the Born effective charges of Al and Yb, which was reported in a previous study, is also shown (black line). Although the average value of the Born effective charge increases as the Yb concentration increases, the charge values of Al and Yb also tend to increase.…”

Section: Resultsmentioning

confidence: 68%

“…This indicates that the bond length of Yb–N is shorter than that of Al–N and the wurtzite structure is compressed in the c -axis direction. In fact, theoretical and experimental investigations have confirmed that the lattice-constant ratio ( c / a ) tends to decrease as the Yb concentration increases. , Therefore, as the concentration of Yb increases, the influence of Δ u Yb–N increases in the wurtzite structure, and the average Δ u also increases, which is thought to contribute to the increase in the total spontaneous polarization.…”

Section: Resultsmentioning

confidence: 98%

“…Recently, significant enhancement of the piezoelectric performance of ytterbium-doped AlN (YbAlN) has been reported through experiments and theoretical calculations. − Based on these reports, addition of Yb to AlN affects the crystal structure, as well as the stability of the wurtzite phase, and YbAIN has good piezoelectric properties. Similar phenomena have also been reported for ScAlN .…”

Section: Introductionmentioning

confidence: 99%

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Spontaneous Polarization and Polarization-Induced Electron Sheet Charge of YbAlN on GaN: A First-Principles Study

Hirata

Kawano

Yamada

et al. 2022

ACS Appl. Electron. Mater.

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The high spontaneous polarization in scandium-doped AlN (ScAlN) is being actively investigated for applications to various electronic devices. In this study, spontaneous polarization of ytterbium-doped AlN (Yb x Al1–x N) was investigated by first-principles calculations. The magnitude of spontaneous polarization increases with increasing Yb concentration and reaches the maximum value of −0.3 C/m2 at x = 0.5, which is comparable with that of ScAlN. Moreover, the results revealed the correlation between the lattice-constant ratio (c/a) of the wurtzite structure and spontaneous polarization. The value of spontaneous polarization is affected by the length of the Yb–N bonds along the c-axis in the wurtzite structure. The shorter Yb–N bonds compared with Al–N bonds and higher Born effective charge of Yb compared with Al are considered to be the main factors for the high spontaneous polarization of YbAlN. The polarization-induced electron sheet charge in YbAlN/GaN heterostructures is estimated to be comparable with that in ScAlN/GaN. These results suggest that YbAlN is a promising barrier layer for GaN-based high-electron-mobility transistors. At low Yb concentration, the lattice mismatch between Yb x Al1–x N and the GaN buffer layer is very small. The polarization-induced interface sheet charge is affected by the sum of the spontaneous and piezoelectric polarization. In the case of YbAlN/GaN, the piezoelectric polarization is suppressed to a low level, and the effect of spontaneous polarization increases and leads to higher polarization-induced interface sheet charge.

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Section: Introductionsupporting

confidence: 71%

Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Spontaneous Polarization and Polarization-Induced Electron Sheet Charge of YbAlN on GaN: A First-Principles Study

Hirata

Kawano

Yamada

et al. 2022

ACS Appl. Electron. Mater.

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“…The latest research report that introduces Yb into aluminum nitride (AlN) leads to a large enhancement in the material's piezoelectric response (d33). The maximum d33 is calculated to be over 100 pC/N, which is 20 times higher than that of AlN (Hirata et al, 2021). However, there are no reports of successful preparation of devices from related materials.…”

Section: Piezoelectric Filmsmentioning

confidence: 89%

A Review of UltraHigh Frequency Ultrasonic Transducers

et al. 2022

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The ultrahigh-frequency (UHF) ultrasonic transducers are active in various fields, including nondestructive evaluation in the semiconductor industry, microscopic biological organization imaging in biomedicine, particle manipulation, and so on. In these fields ultrahigh-frequency (UHF) ultrasonic transducers play a critical role in the performance of related equipment. This article will focus on the topic of ultrahigh-frequency ultrasonic transducers’ preparation, and reviews three aspects: material selection, focus design, and acoustic energy transmission matching. Provides a summary of the current research status, and puts forward some views on the future development of UHF ultrasound devices.

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Lattice Distortion and Piezoelectricity Enhancement in GaN by Alloying with Group III and Rare‐Earth Elements: A Comparative Experimental Study

Uehara

Amano

Mizuno

et al. 2023

Physica Rapid Research Ltrs

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The lattice of wurtzite nitrides such as gallium nitride (GaN) and aluminum nitride (AlN) is distorted by alloying with scandium (Sc). This lattice distortion, which entails a decrease in the lattice constant ratio c/a, leads to a significant improvement in piezoelectricity and the appearance of ferroelectricity, which are attractive properties for material applications. However, systematic studies on the effect of different alloying elements on the lattice distortion of wurtzite nitrides are scarce and restricted to theoretical investigations. Herein, the experimental investigation of the lattice distortion and its influence on the piezoelectricity of cosputtering‐prepared thin films of GaN alloyed with group III and rare‐earth elements other than Sc, that is, yttrium, dysprosium, and ytterbium is described. All the investigated elements greatly reduce the lattice constant ratio of GaN from 1.63 to 1.61 and cause a twofold increase in the piezoelectric charge coefficient. Therefore, it is indicated in the experimental results that alloying with elements other than Sc also results in the distortion of the crystal lattice and the enhancement of the piezoelectric properties of GaN. Furthermore, regardless of the particular alloying element used, a correlation between lattice distortion and piezoelectricity is experimentally demonstrated.

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Significant Enhancement of Piezoelectric Response in AlN by Yb Addition

Cited by 18 publications

References 36 publications

Spontaneous Polarization and Polarization-Induced Electron Sheet Charge of YbAlN on GaN: A First-Principles Study

Spontaneous Polarization and Polarization-Induced Electron Sheet Charge of YbAlN on GaN: A First-Principles Study

A Review of UltraHigh Frequency Ultrasonic Transducers

Lattice Distortion and Piezoelectricity Enhancement in GaN by Alloying with Group III and Rare‐Earth Elements: A Comparative Experimental Study

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