Agne Zukauskaite

• PhD
• Project Manager at Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology

Aluminum scandium nitride (Al1−xScxN with x = 0–0.41) thin films were deposited by reactive pulsed-DC magnetron sputtering on Si(001) and Al2O3(0001) substrates. X-ray diffraction indicated high degree of c-axis orientation in all the films, and based on pole figure measurements, epitaxial relationship could be defined as [101⎯⎯0]AlScN//[112⎯⎯0]sap...

Wurtzite Al1−xScxN thin films with scandium Sc concentrations up to x = 0.41 were prepared by reactive pulsed DC magnetron co-sputtering at heater temperatures between 300 °C and 400 °C on Al2O3 substrates. Spectroscopic ellipsometry was used to determine the dielectric functions of wurtzite Al1−xScxN by modeling the spectra with a three-layer mode...

For the first time, non-polar a-plane Al0.77Sc0.23N(11-20) thin films were prepared by magnetron sputter epitaxy on r‑plane Al2O3(1-102) substrates. Different substrate off-cut angles were compared, the off-cut angle of 3{degree sign} resulted in the best structural quality of AlScN layer. After the structural characterization by X-ray diffraction...

A novel additive manufacturing route using a tailored resin containing Poly(vinylidene fluoride) Trifluoroethylene (PVDF‐TrFE) to 3D print piezoelectric films is demonstrated. Piezoelectric films are printed within 2 seconds in a single step by simultaneously focusing initiating and inhibiting excitations within the liquid resin to locally confine...

Ambient energy harvesting has great potential to contribute to sustainable development and address growing environmental challenges. Converting waste energy from energy-intensive processes and systems (e.g., combustion engines and furnaces) is crucial to reducing their environmental impact and achieving net-zero emissions. Compact energy harvesters...

The increasing demand for More than Moore devices requires epitaxy technology to keep up with the discovery and deployment of new semiconductors. An emerging technology for cost-effective, device-quality growth is magnetron sputter epitaxy, though detailed studies on the process itself remain scarce. Here, we report an extensive study on the correl...

The enhanced piezoelectric properties of aluminum scandium nitride (Al1−xScxN or AlScN) were discovered in 2009 by Morito Akiyama’s team [...]

Owing to their very large piezoelectric coefficients and spontaneous polarizations, (Sc,Y)xAl1−xN alloys have emerged as a new class of III-nitride semiconductor materials with great potential for high-frequency electronic and acoustic devices. The thermal conductivity of constituent materials is a key parameter for design, optimization, and therma...

Piezoelectric Thin Films In article number 2200380, Akash Nair and colleagues report on the synthesis of a‐plane Al0.7Sc0.3N thin films grown on r‐plane Al2O3 substrates with off‐cuts using magnetron sputter epitaxy. The influence of sputtering conditions on relevant film properties is investigated, based on which a growth model for promoting non‐p...

III-V solid solutions are sensitive to growth conditions due to their stochastic nature. The highly crystalline thin films require a profound understanding of the material properties and reliable means of their determination. In this work, we have investigated the Raman spectral fingerprint of Al1−xScxN thin films with Sc concentrations x = 0, 0.14...

The laser ultrasound (LU) technique has been used to determine dispersion curves for surface acoustic waves (SAW) propagating in AlScN/Al2O3 systems. Polar and non-polar Al0.77Sc0.23N thin films were prepared by magnetron sputter epitaxy on Al2O3 substrates and coated with a metal layer. SAW dispersion curves have been measured for various propagat...

This work uses a surface acoustic wave (SAW) magnetic field sensor for measurement and closed-loop current control of the inductor current in a GaN-based dc-dc power converter. The sensor is based on aluminium scandium nitride (AlScN) thin films with relatively high Sc concentration of 32%, and fabricated on low-cost 8-inch silicon substrate, with...

Photoconduction (PC) properties were investigated for ternary indium aluminium nitride (InxAl1−xN) nanorods (NRs) with different indium composition (x) from 0.35 to 0.68, as grown by direct-current reactive magnetron sputter epitaxy. Cross-sectional scanning transmission electron microscopy (STEM) reveals single-crystal quality of the vertically al...

A‐plane Al0.7Sc0.3N( 11 2 ¯ 0 ) thin films are grown on r‐plane Al2O3( 1 1 ¯ 02 ) substrates using reactive pulsed‐DC magnetron sputter epitaxy. This is the first report of successful synthesis of non‐polar epitaxial AlScN films with a high scandium concentration (30%). The influence of different sputtering conditions, such as magnetron power, temp...

Ferroelectric thin films of wurtzite-type aluminum scandium nitride (Al1−xScxN) are promising candidates for non-volatile memory applications and high-temperature sensors due to their outstanding functional and thermal stability exceeding most other ferroelectric thin film materials. In this work, the thermal expansion along with the temperature st...

Piezoelectric micromirrors with aluminum nitride (AlN) and aluminum scandium nitride (Al0.68Sc0.32N) are presented and compared regarding their static deflection. Two chip designs with 2 × 3 mm2 (Design 1) and 4 × 6 mm2 (Design 2) footprint with 600 nm AlN or 2000 nm Al0.68Sc0.32N as piezoelectric transducer material are investigated. The chip with...

In this work, the first surface acoustic-wave-based magnetic field sensor using thin-film AlScN as piezoelectric material deposited on a silicon substrate is presented. The fabrication is based on standard semiconductor technology. The acoustically active area consists of an AlScN layer that can be excited with interdigital transducers, a smoothing...

In this work, surface acoustic wave (SAW) modes and their dependence on propagation directions in epitaxial Al0.68Sc0.32N(0001) films on Al2O3(0001) substrates were studied using numerical and experimental methods. In order to find optimal propagation directions for higher-order SAW modes, phase velocity dispersion branches of Al0.68Sc0.32N on Al2O...

Scandium-alloying of aluminum nitride (AlScN) enhances the piezoelectric properties of the material and increases the performance of piezoelectric microelectromechanical systems (MEMS). However, this enhancement is caused by the destabilization of the wurtzite phase and so far the stability of AlScN thin films has not been sufficiently studied. Sta...

1 µm thick non-polar a-plane AlScN(112 0 thin films were prepared by magnetron sputter epitaxy on r-plane Al2O3(11 02) substrates. X-ray diffraction (XRD) measurements confirmed it as a single-phase wurtzite a-plane AlScN (112 0. Surface acoustic wave (SAW) resonators with wavelengths λ = {2, 2.5, 3, 4, 5, 6, 7, 8, 10} µm were fabricated on a-plane...

Al1−xScxN (AlScN) is known for its large elastic and piezoelectric constants and thus is a favorable material for applications in novel radio frequency (RF) components. We investigated a-plane AlScN on r-plane Al2O3 (AlScN(11-20)/Al2O3(1-102)). The surface acoustic wave (SAW) propagation properties of AlScN(11-20)/Al2O3(1-102) and AlScN(11-20)/Al2O...

1 µm thick sputtered Al1-xScxN films were used to fabricate SAW resonators with 2-20 µm wavelength and the frequency response was measured in the range of 20 °C to 140 °C. Extracted phase velocity dispersion curve was in good agreement with the simulated dispersion curve by FEM model. Moreover, for each investigated temperature, the corresponding p...

Alloys of scandium with AlN exhibit an enhanced piezoelectric coefficient that can boost the performance of nitride‐based electronic and opto‐electronic devices such as high mobility electron transistors (HEMTs).Consequently, there is increasing interest in the epitaxial growth of high‐quality AlScN/GaN heterostructures. So far, only very recent re...

In this work, all electroacoustic material parameters, i.e., the elastic, piezoelectric, and dielectric coefficients, as well as the mass density, were determined experimentally for wurtzite aluminum scandium nitride (Al1−xScxN) for a wide range of Sc concentrations of up to x = 0.32 from the same material source for the first time. Additionally, t...

Performance of SAW resonators fabricated on AlScN/Si and AlScN/Al2O3 thin films to investigate the influence of substrate.

Heteroepitaxy of diamond on single-crystalline iridium via bias enhanced nucleation remains the most successful, and simultaneously, the most unexplored crystallization process developed for fabrication of wafer-scale thin films and free-standing substrates. Unique conditions provided by nucleation and growth from “soft-implanted” carbon clusters c...

It has been found that introducing Sc into AIN to form Al1-xScxN can lead to a significant increase in piezoelectric response, making Al1-xScxN a promising material for electroacoustic devices, such as frequency filters for mobile communications. 1 μm thick highly c-axis oriented Al1-xScxN thin films were deposited on 100 mm Si(001) (x = 0, 0.14, 0...

In this paper, we investigate the temperature cross-sensitivity of aluminum nitride (AlN)-based flexural plate wave devices for sensing applications in contact with liquids. In our improved device topology, the interdigital transducers are designed as a buried electrode, and thus, are electrically shielded, enabling full immersion of the sensor int...

The piezoelectric and pyroelectric properties of aluminum nitride (AlN) can be further enhanced by alloying AlN with scandium nitride (ScN). However, while the pyroelectric effect can strongly affect the performance of electroacoustic devices such as surface acoustic wave (SAW) resonators, the pyroelectric properties of aluminum scandium nitride (A...

We present the epitaxial growth of ferroelectric potassium tantalate-niobate (KTN) thin films by pulsed laser deposition. As a result of the optimization of the deposition and the surface finishing processes, a c-axis oriented KTa0.5Nb0.5O3 thin film with homogeneous polarization phase grown on KTaO3 and an efficient KTa0.5Nb0.5O3 waveguiding thin...

Scandium aluminum nitride (ScAlN) films have been synthesized by pulsed-DC reactive magnetron sputtering. The degree of c-axis orientation as well as piezoelectric characteristics of the Sc0.26Al0.74N thin films grown on Si (001) at various discharge powers and processing pressures values have been investigated. According to x-ray diffraction (XRD)...

Reactive pulsed DC magnetron co-sputtering was used to grow piezoelectric aluminium nitride (AlN) and aluminium scandium nitride (AlScN) thin films on Si(001) substrates. By using grazing incidence X-ray diffraction (GIXRD), scanning electron microscopy (SEM), and piezoresponse force microscopy (PFM), we investigate how the microstructure and the p...

Aluminum nitride (AlN) based flexural plate wave (FPW) sensors with buried interdigital transducers (IDTs) were designed, fabricated, and characterized with respect to their application as sensors operating in liquids. In the proposed device, the IDTs are designed as a buried electrode, and thus, are electrically shielded, enabling full immersion o...

Nanoindentation measurements along with atomic force microscopy, X-ray diffraction, and residual stress analyses on the basis of Raman measurements have been performed to characterize stress-tailored AlN thin films grown using reactive RF magnetron sputtering. The intrinsic stress gradient caused by the growing in-plane grain size along film thickn...

Potassium tantalate-niobate mixed crystal (KTN) thin films are promising candidates to meet the needs of integrated nonlinear optical devices for electro-optic and frequency-conversion applications. In this contribution we report on pulsed-laser-deposition growth of ferroelectric KTN films on MgO substrates. It was shown that highly-oriented KTN fi...

In this work, the adhesive wafer bonding of diamond thin films onto 8″ silicon substrates is reported. In order to characterize bonded nano-crystalline diamond layers, vibrometry and interferometry studies of micro-fabricated flexural beam and disk resonators were carried out. In particular, surface topology along with resonant frequencies, eigenmo...

Aluminum nitride (AlN) thin films deposited by reactive radio frequency magnetron sputtering in an Ar/N2 discharge on Si(001) substrates were studied with respect to structure, stress, and piezoelectric properties. In order to optimize the AlN layers for flexural plate wave (FPW) devices, the influence of process pressure and N2 concentration has b...

A great potential of the use of aluminum nitride(AlN) to enhance the actuation of nanocrystalline diamond (NCD) microelectromechanical system disk resonators is revealed. A disk resonator with a unimorph (AlN/NCD) structure is fabricated by depositing a c-axis oriented AlN on a capacitive NCD disk resonator. The unimorph resonator is piezoelectrica...

YAlN is a new member of the group-III nitride family with potential for applications in next generation piezoelectric and light emitting devices. We report the infrared dielectric functions and optical phonons of wurtzite (0001) Yx Al1−x N epitaxial films with 0 ≤ x ≤ 0.22. The films are grown by magnetron sputtering epitaxy on c-plane Al2O3 and th...

Pseudomorphic stabilization in wurtzite ScxAl1−xN/AlN and ScxAl1−xN/InyAl1−yN superlattices (x = 0.2, 0.3, and 0.4; y = 0.2–0.72), grown by reactive magnetron sputter epitaxy was investigated. X-ray diffraction and transmission electron microscopy show that in ScxAl1−xN/AlN superlattices the compressive biaxial stresses due to positive lattice mism...

Nanoindentation with in-situ electrical characterization is used to investigate piezoelectric scandium aluminum nitride (ScxAl1−xN) thin films with Sc contents up to x = 0.3. The films are prepared by reactive magnetron sputtering using Al2O3 substrates with TiN seed layers as bottom electrodes at a substrate temperature of 400 °C. X-ray diffractio...

By combining theoretical prediction and experimental verification we investigate the piezoelectric properties of yttrium indium nitride (YxIn1-xN). Ab initio calculations show that the YxIn1-xN wurtzite phase is lowest in energy among relevant alloy structures for 0 < x < 0:5. Reactive magnetron sputter epitaxy was used to prepare thin films with Y...

We study wurtzite YxAl1-xN (0≤ x ≤ 0.22) films with (0001) orientation deposited by magnetron sputtering epitaxy on Si(100) substrates and we determine the alloys band gap energies and optical constants. Room temperature spectroscopic ellipsometry (SE) is employed in the energy range from 1 to 6.3 eV, and data modeling based on the standard dielect...

Reactive magnetron sputtering was used to deposit YxAl1−xN thin films, 0 ≤ x ≤ 0.22, onto Al2O3(0 0 0 1) and Si(1 0 0) substrates. X-ray diffraction and analytical electron microscopy show that the films are solid solutions. Lattice constants increase with Y concentration, in agreement with ab initio calculations. Spectroscopic ellipsometry measure...

Piezoelectric wurtzite Sc xAl 1-xN (x=0, 0.1, 0.2, 0.3) thin films were epitaxially grown by reactive magnetron co-sputtering from elemental Sc and Al targets. Al 2O 3(0001) wafers with TiN(111) seed and electrode layers were used as substrates. X-ray diffraction shows that an increase in the Sc content results in the degradation of the crystalline...

The hardness, Young’s modulus, friction coefficient, and piezoelectric response during nanoindentation of ScxAl1-xN (0 ≤ x ≤0.2) thin films have been investigated. Films of 250-500 nm thick were deposited by reactive magnetron sputtering from elemental Al and Sc targets onto Al2O3(0001) substrates with a conductive TiN(111) seed layer, at substrate...

Thermoelectric properties of ScN thin films grown by reactive magnetron sputtering on Al2O3(0001) wafers are reported. X-ray diffraction and elastic recoil detection analyses show that the composition of the films is close to stoichiometry with trace amounts (∼1 at. % in total) of C, O, and F. We found that the ScN thin-film exhibits a rather low e...

AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0 ≤ x ≤ 0.3) thin films grown by dual reactive magnetron sputtering exhibited...

AlN(0001) was alloyed with ScN with molar fractions up to ∼22 % , while retaining a single-crystal wurtzite (w-) structure and with lattice parameters matching calculated values. Material synthesis was realized by magnetron sputter epitaxy of thin films starting from optimal conditions for the formation of w-AlN onto lattice-matched w-AlN seed laye...

AlN is challenged as the material choice in important thin film electroacoustic devices for modern wireless communication applications. We present the promise of superior electromechanical coupling (kt2), in w−ScxAl1−xN by studying its dielectric properties. w−ScxAl1−xN (0≤x≤0.3) thin films grown by dual reactive magnetron sputtering exhibited low...