Strong enhancement of piezoelectric constants in Sc<i>x</i>Al1−<i>x</i>N: First-principles calculations

Momida, Hiroyoshi; Teshigahara, Akihiko; Oguchi, Tamio

doi:10.1063/1.4953856

Cited by 46 publications

(38 citation statements)

References 33 publications

(38 reference statements)

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“…The d 33 and the d 33,f of w-AlN are 4.08 pC/N and 5.27 pC/N, respectively, which are in good agreement with the experimentally reported values of 4.0 pC/N and 5.56 pC/N, respectively [40]. All the co-dopants increase both the total d 33 and the d 33,f of w-AlN (shown in Figure 3 [10,11] and theoretical values [41,12,35]. Additionally, Figure 3(a) shows a good agreement between our measured and calculated d 33 for w-AlN as well as Sc doping.…”

Section: Resultssupporting

confidence: 88%

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Noor‐A‐Alam

Olszewski

Campanella

et al. 2020

ACS Appl. Mater. Interfaces

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Based on density functional theory, we show that Li andX (X=V, Nb and Ta) co-doping in 1Li:1X ratio broadens thecompositional freedom for significant piezoelectric enhancement in w-AlN, promising them to be good alternatives of expensive Sc. Interestingly, these co-doped w-AlN also show quite large spontaneous electric polarization about 0.80 C/m2 with the possibility of ferroelectric polarization switching, opening new possibilities in wurtzite nitrides. Increase in piezoelectric stress constant (e33) with decrease in elastic constant ( C33 ) results enhancement in piezoelectric strain constant ( d33 ), which is desired for improving the performance of resonators for high frequency RF signals. Also, these co-doped w-AlN are potential lead-free piezoelectric materials for energy harvesting and sensors as they improve the longitudinal electromechanical coupling constant (K^2 33), transverse piezoelectric strain constant (d31), and figure of merit for power generation. However, the enhancement in K^2 33 is not as pronounced as that in d33, because co-doping increases the dielectric constant. The longitudinal acoustic wave velocity (7.09 km/s) of Li0.1875Ta0.1875Al0.625N is quite comparable with that of commercially used piezoelectric LiNbO3 or LiTaO3 in special cuts (about 5~7 km/s) despite the fact that the acoustic wave velocities drop with co-doping or Sc concentration. File list (2)download file view on ChemRxiv codoped-AlN.pdf (0.93 MiB) download file view on ChemRxiv codoped-

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Section: Resultssupporting

confidence: 88%

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Noor‐A‐Alam

Olszewski

Campanella

et al. 2020

ACS Appl. Mater. Interfaces

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“…9,20,25) For the calculated wurtzite materials, the first (clamped ion) term shows relatively small negative values and does not significantly depend on material. The second (internal strain) term dominantly contributes to the trend of e 33 versus c=a shown in Fig.…”

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confidence: 91%

Effects of lattice parameters on piezoelectric constants in wurtzite materials: A theoretical study using first-principles and statistical-learning methods

Momida

Oguchi

2018

Appl. Phys. Express

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Longitudinal piezoelectric constant (e 33 ) values of wurtzite materials, which are listed in a structure database, are calculated and analyzed by using first-principles and statistical learning methods. It is theoretically shown that wurtzite materials with high e 33 generally have small lattice constant ratios (c/a) almost independent of constituent elements, and approximately expressed as e 33 / c/a % (c/a) 0 with ideal lattice constant ratio (c/a) 0 . This relation also holds for highly-piezoelectric ternary materials such as Sc x Al 1%x N. We conducted a search for high-piezoelectric wurtzite materials by identifying materials with smaller c/a values. It is proposed that the piezoelectricity of ZnO can be significantly enhanced by substitutions of Zn with Ca. © 2018 The Japan Society of Applied Physics I n recent times, owing to their suitable mechanical and semiconducting properties, piezoelectric wurtzite semiconductors such as ZnO and GaN have received a lot of attention in the form of piezotronics and piezo-phototronics device materials.1) The wurtzite-type piezoelectric materials, especially AlN, have another advantage that these can be used in high-temperature environments, e.g., as sensors in automobile engines, because their noncentrosymmetric structures are stable even at high temperatures.2,3) However, the piezoelectric constants of wurtzite-type materials are generally much smaller than those of the perovskite-based materials such as Pb(Zr x Ti 1−x )O 3 , known as PZT, by few orders. It remains a challenge to explore better piezoelectric wurtzite materials; there are many reports aiming to enhance piezoelectricity by element doping or codoping into parent materials. 4-7)Among the wurtzite materials, the highest piezoelectricity has been experimentally discovered for Sc x Al 1−x N (about 25 pC=N for x ∼ 0.5).2,3) First-principles calculations have shown the microscopic effects of Sc on the piezoelectricity in Sc x Al 1−x N by demonstrating an enhancement in piezoelectricity with increase in x. 8,9) Tasnádi et al. have revealed that the piezoelectric enhancement comes from the large responses of atomic positions to external strain and the significant softening of elastic constant. 8) However, novel materials which are superior to Sc x Al 1−x N have not been synthesized yet as there are no clear and general material-design criteria practically usable for enhancing the piezoelectricity of wurtzite materials. It has been proposed theoretically that there exists a relationship between piezoelectricity and microscopic structures, 10) but the physical mechanism behind the relation with intricate parameters is not fully understood yet. Therefore, better understanding of piezoelectricity in wurtzite materials might lead to simple design criteria making it possible to find a controllable key parameter describing wurtzite piezoelectricity with the help of first-principles and machine learning techniques which have generated a great interest in the recent times. 11,12) In this study, we calculate longitudinal...

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“…This relationship has been demonstrated to apply to a large range of wurtzite-structure piezoelectric material systems which have c/a ratios larger than 1.5, including representative wurtzite-structure oxides (BeO, MgO, ZnO), nitrides (BN, AlN, GaN, InN, Sc 0.5 Al 0.5 N, and related alloys X 0.5 Zn 0.5 N where X = Mg, Ca, Sr, and Ba), sulfides, selenides, tellurides, and iodides, and is based on an examination of the correlation between e 33 and c/a from experimental measurements and first-principles predictions. [30][31] In our More specifically, d 33 increases from 3.2 to 4.5 and 6.2 pC/N for x = 0, 0.20 and 0.36, reaches a maximum of d 33 = 6.4 pC/N for x = 0.48, and decreases to 5.9, 6.3, 6.3 pC/N for x = 0.62, 0.79, and 1.00, respectively. The inset also includes as black bar the reported d = 4.2 pC/N for AlN, [5a, 30,32] illustrating that the maximum piezoelectric response for (Ti 1−x Mg x ) 0.25 Al 0.75 N layers at x = 0.5 is 50% larger than that of the pure AlN matrix.…”

Section: Resultsmentioning

confidence: 99%

Structural Stabilization and Piezoelectric Enhancement in Epitaxial (Ti₁₋_xMg_x)_0.25Al_0.75N(0001) Layers

Wang

Aryana

Gaskins

et al. 2020

Adv Funct Materials

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Epitaxial (Ti 1−x Mg x ) 0.25 Al 0.75 N(0001)/Al 2 O 3 (0001) layers are used as a model system to explore how Fermi-level engineering facilitates structural stabilization of a host matrix despite the intentional introduction of local bonding instabilities that enhance the piezoelectric response. The destabilizing octahedral bonding preference of Ti dopants and the preferred 0.67 nitrogen-to-Mg ratio for Mg dopants deteriorate the wurtzite AlN matrix for both Ti-rich (x < 0.2) and Mg-rich (x ≥ 0.9) alloys. Conversely, x = 0.5 leads to a stability peak with a minimum in the lattice constant ratio c/a which is caused by a Fermi-level shift into the bandgap and a trend towards non-directional ionic bonding, leading to a maximum in the expected piezoelectric stress constant e 33 . The refractive index and the sub-gap absorption decrease with x, the optical band gap increases, and the elastic constant along the hexagonal axis C 33 = 270±14 GPa remains composition independent, leading to an expected piezoelectric constant d 33 = 6.4 pC/N at x = 0.5 which is 50% larger than for the pure AlN matrix. Thus, contrary to the typical anti-correlation between stability and electromechanical coupling, the (Ti 1−x Mg x ) 0.25 Al 0.75 N system exhibits simultaneous maxima in the structural stability and the piezoelectric response at x = 0.5.

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Strong enhancement of piezoelectric constants in ScxAl1−xN: First-principles calculations

Cited by 46 publications

References 33 publications

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Effects of lattice parameters on piezoelectric constants in wurtzite materials: A theoretical study using first-principles and statistical-learning methods

Structural Stabilization and Piezoelectric Enhancement in Epitaxial (Ti₁₋_xMg_x)_0.25Al_0.75N(0001) Layers

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Strong enhancement of piezoelectric constants in ScxAl1−xN: First-principles calculations

Cited by 46 publications

References 33 publications

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Large Piezoelectric Response and Ferroelectricity in Li and V/Nb/Ta Co-Doped w-AlN

Effects of lattice parameters on piezoelectric constants in wurtzite materials: A theoretical study using first-principles and statistical-learning methods

Structural Stabilization and Piezoelectric Enhancement in Epitaxial (Ti1−xMgx)0.25Al0.75N(0001) Layers

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Structural Stabilization and Piezoelectric Enhancement in Epitaxial (Ti₁₋_xMg_x)_0.25Al_0.75N(0001) Layers