Article
Physics, Applied
Wanlin Zhu, John Hayden, Fan He, Jung-In Yang, Pannawit Tipsawat, Mohammad D. Hossain, Jon-Paul Maria, Susan Trolier-McKinstry
Summary: This study reveals the temperature dependence of ferroelectric switching in Al0.84Sc0.16N, Al0.93B0.07N, and AlN thin films, showing strong temperature dependence on polarization reversal and coercive field, while minimal temperature dependence on remanent polarization values. The relative permittivity increased within a certain temperature range, and polarization reversal was confirmed through piezoelectric coefficient analysis and chemical etching. Models based on thermal activation suggest a distribution of pinning sites or nucleation barriers regulates the switching behavior with an average activation energy near 28 meV.
APPLIED PHYSICS LETTERS
(2021)
Article
Materials Science, Multidisciplinary
C. Yuan, M. Park, Y. Zheng, J. Shi, R. Dargis, S. Graham, A. Ansari
Summary: This study investigates phonon scattering processes and thermal conductivity in Al1-xScxN alloys grown by molecular beam epitaxy. The results show a decreasing trend in thermal conductivity with increasing scandium content, with an increase in thermal conductivity with temperature below 200 K and a plateau at higher temperatures. Application of an analytical model helps estimate the effects of scattering mechanisms on thermal conductivity behavior.
MATERIALS TODAY PHYSICS
(2021)
Article
Physics, Applied
Md Redwanul Islam, Niklas Wolff, Mohamed Yassine, Georg Schoenweger, Bjorn Christian, Hermann Kohlstedt, Oliver Ambacher, Fabian Lofink, Lorenz Kienle, Simon Fichtner
Summary: This study found that the ferroelectric-to-paraelectric transition temperature of Al1-xScxN thin film can exceed 1100 degrees C, surpassing the transition temperature of virtually any other thin film ferroelectric. Through high-temperature X-ray diffraction and permittivity measurements, it was discovered that the wurtzite-type structure of Al0.73Sc0.27N remains stable during the entire 1100 degrees C annealing cycle.
APPLIED PHYSICS LETTERS
(2021)
Article
Chemistry, Physical
Wenzheng Jiang, Lei Zhu, Lingli Chen, Yumeng Yang, Xi Yu, Xiaolong Li, Zhiqiang Mu, Wenjie Yu
Summary: In this study, an in situ method based on synchrotron X-ray diffraction (XRD) system was proposed to characterize the longitudinal piezoelectric constant d(33) of Al1-xScxN film. The measurement results showed the piezoelectric effect of Al1-xScxN films by lattice spacing variation upon applied external voltage. The in situ synchrotron XRD measurement was proven to be an effective method for precise piezoelectric coefficient d(33) characterization.
Article
Chemistry, Physical
Yishui Ding, Xiangyu Hou, Tengyu Jin, Yanan Wang, Xu Lian, Yuan Liu, Yihe Wang, Sisheng Duan, Xiangrui Geng, Meng Wang, Jingyu Mao, Yuanyuan Zhang, Peirong Tang, Minghua Li, Huamao Lin, Yao Zhu, Siewlang Teo, Qiang Zhu, Ming Lin, Wei Chen
Summary: In this study, the growth mechanism and interfacial chemistry of ultrathin platinum and molybdenum films on high-crystalline Al1-xScxN surface were investigated. The chemical and electronic structure evolution of the interface during the deposition process were examined using in-situ X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy. The structural properties of the interface were characterized by cross-sectional transmission electron microscopy, X-ray diffraction spectroscopy, and atomic force microscopy. The study reveals the formation of ionic Pt2+-N bonds at the Pt/Al1-xScxN interface, while molybdenum does not bond with the substrate. Furthermore, electron transfer induces upward band-bending effects on the Al1-xScxN surface upon both platinum and molybdenum interactions. The research on the chemical and structural properties of ultrathin metal electrodes and Al1-xScxN interfaces provides guidance for designing high-performance micro-electromechanical devices.
APPLIED SURFACE SCIENCE
(2023)
Article
Chemistry, Analytical
Niklas Wolff, Md Redwanul Islam, Lutz Kirste, Simon Fichtner, Fabian Lofink, Agne Zukauskaite, Lorenz Kienle
Summary: Research on wurtzite-type aluminum scandium nitride (Al1-xScxN) thin films revealed an anomalous thermal expansion at high temperatures, attributed to the coupling contributions of intrinsic and extrinsic factors. This finding is significant for the manufacturing and operation of Al1-xScxN-based devices.
Article
Physics, Applied
N. M. Feil, E. Mayer, A. Nair, B. Christian, A. Ding, C. Sun, S. Mihalic, M. Kessel, A. Zukauskaite, O. Ambacher
Summary: The study investigated the SAW modes in epitaxial Al0.68Sc0.32N(0001) films on Al2O3(0001) substrates, highlighting enhanced wave guidance and electromechanical coupling for the Sezawa mode in the <1<1>00> propagation direction. Additionally, simulations using finite element method and Green function approach identified different wave types, including Rayleigh, Sezawa, and shear-horizontal wave modes. Selecting high mass density electrodes and specific Sc concentration x in combination with SAW propagation direction could result in increased electromechanical coupling and phase velocities for the Sezawa mode.
JOURNAL OF APPLIED PHYSICS
(2021)
Article
Chemistry, Multidisciplinary
Nizar Ben Moussa, Mohamed Lajnef, Nessrine Jebari, Cedric Villebasse, Fabien Bayle, Julien Chaste, Ali Madouri, Radouane Chtourou, Etienne Herth
Summary: In this study, low-cost sol-gel spin-coating technique was used to synthesize eco-friendly ZnO multilayer films with excellent optical properties and specific orientation suitable for piezoelectric applications. The ZnO sol-gel thin-films using precursor solutions of molarity 0.75 M exhibited an average optical transparency above 98% and an optical band gap energy of 3.42 eV, showing potential for eco-friendly and cost-effective applications in complementary metal-oxide-semiconductor (CMOS) and integrated circuits (IC).
Article
Green & Sustainable Science & Technology
Etienne Herth, Jean-Yves Rauch
Summary: This study demonstrates a successful and environmentally friendly method for depositing dielectric thin films without nitrous oxide at low temperatures. Deposition rates range from 10 to 20 nm/min depending on power, pressure, and gas flows, making it suitable for a wide range of applications requiring low hydrogen content and a stable process.
INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND MANUFACTURING-GREEN TECHNOLOGY
(2022)
Article
Physics, Applied
Caroline Schwinge, Kati Kuehnel, Jennifer Emara, Lisa Roy, Kati Biedermann, Wenke Weinreich, Sabine Kolodinski, Maciej Wiatr, Gerald Gerlach, Maik Wagner-Reetz
Summary: The power factor of CMOS-compatible SiGe films was investigated, and a high power factor was achieved by controlling the doping concentration. The results demonstrate the potential of SiGe as a promising material for the production of thermoelectric embedded applications.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Gilles F. Feutmba, Artur Hermans, John P. George, Hannes Rijckaert, Irfan Ansari, Dries Van Thourhout, Jeroen Beeckman
Summary: This study introduces the use of PZT thin films as on-chip nonlinear devices, demonstrating efficient tuning of chi((2)) and generation of strong second-harmonic signals. The high second-order nonlinearity and tunability of PZT thin films show potential for highly efficient on-chip nonlinear devices.
ADVANCED OPTICAL MATERIALS
(2021)
Article
Physics, Applied
Roman Potjan, Marcus Wislicenus, Oliver Ostien, Raik Hoffmann, Maximilian Lederer, Andre Reck, Jennifer Emara, Lisa Roy, Benjamin Lilienthal-Uhlig, J. Wosnitza
Summary: This study demonstrates the fully CMOS-compatible fabrication of HfN and ZrN thin films and investigates their physical properties. The results show that HfN and ZrN samples exhibit superconducting phase transitions and have high critical temperatures and fields, indicating their potential application in quantum computing and related fields.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
John Hayden, Joseph Shepard, Jon-Paul Maria
Summary: Ferroelectric Al0.93B0.07N thin films were prepared on (100) Si substrates with the necessary c-axis out-of-plane orientation achieved through initial plasma treatment and subsequent layer growth. The resulting films exhibited strong polarization hysteresis, making them useful for integration with mainstream semiconductors.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
Junji Kataoka, Sung-Lin Tsai, Takuya Hoshii, Hitoshi Wakabayashi, Kazuo Tsutsui, Kuniyuki Kakushima
Summary: Research on 50 nm thick ferroelectric Al0.78Sc0.22N films with TiN electrodes revealed that the leakage current gradually shifted during initial switching, stabilizing at a specific value. This change was interpreted as the formation of a tunneling barrier due to nitrogen vacancies at the metal interface.
JAPANESE JOURNAL OF APPLIED PHYSICS
(2021)
Article
Physics, Applied
Johannes Hertel, Caroline Schwinge, Lukas Gerlich, Maik Wagner-Reetz
Summary: In this study, the thermoelectric properties of Ru2Si3 thin films were characterized, showing exceptionally high Seebeck coefficients close to room temperature in dependency of adjustable oxide nanoskins formed via rapid thermal processing.
APPLIED PHYSICS LETTERS
(2022)
Article
Materials Science, Multidisciplinary
Dixiong Wang, Pariasadat Musavigharavi, Jeffrey Zheng, Giovanni Esteves, Xiwen Liu, Merrilyn Mercy Adzo Fiagbenu, Eric A. Stach, Deep Jariwala, Roy H. Olsson
Summary: The study measured and compared the frequency-dependent ferroelectric properties of 45 nm (Al,Sc)N films sputter deposited on CMOS-compatible Al metal electrodes, showing low in-plane compressive stress and an imprint in coercive fields at 10 kHz. Utilizing PUND measurements, ferroelectric switching was observed within approximately 200 ns of applied voltage pulse, demonstrating the ability of (Al,Sc)N to achieve fast read/write speeds in memory devices.
PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS
(2021)
Article
Physics, Applied
Jeffrey X. Zheng, Dixiong Wang, Pariasadat Musavigharavi, Merrilyn Mercy Adzo Fiagbenu, Deep Jariwala, Eric A. Stach, Roy H. Olsson
Summary: The study investigates the effects of a multilayer architecture on the electrical breakdown strengths and ferroelectric characteristics of AlScN films. Multilayer films demonstrate higher characteristic breakdown fields and breakdown field to coercive field ratios compared to single layer films, with no significant change in remanent polarization. The enhancement in characteristic breakdown field is attributed to deflection of electrical tree propagation by multilayer interfaces and relative compressive stress in alternating layers.
JOURNAL OF APPLIED PHYSICS
(2021)
Correction
Nanoscience & Nanotechnology
Valerie Yoshioka, Jian Lu, Zichen Tang, Jicheng Jin, Roy H. Olsson, Bo Zhen
Article
Engineering, Electrical & Electronic
Rossiny Beaucejour, Volker Roebisch, Abhay Kochhar, Craig G. Moe, Michael David Hodge, Roy H. Olsson
Summary: This study demonstrates the deposition of high Sc alloying levels AlScN films on silicon with controlled stress and without the formation of anomalous grains (AOGs) using reactive sputtering. It is shown that a gradient seed layer and proper process gas mixture can inhibit the formation of AOGs even at high Sc alloying levels. The total flow is found to control the average film stress, while the process gas mixture mainly affects the density of AOG formation. Bulk acoustic wave resonators fabricated from low stress and AOG-free Al0.68Sc0.32N films grown directly on Si exhibit high frequency operation, high electromechanical coupling, and high quality factors.
JOURNAL OF MICROELECTROMECHANICAL SYSTEMS
(2022)
Article
Chemistry, Analytical
Zichen Tang, Giovanni Esteves, Jeffrey Zheng, Roy H. Olsson
Summary: Due to their favorable electromechanical properties, Aluminum Nitride (AlN) and Aluminum Scandium Nitride (Al1-xScxN) thin films have been widely used in radio frequency (RF) acoustic devices. However, the resistance to etching at high scandium alloying has hindered the realization of devices that can fully utilize the highest electromechanical coupling coefficients. In this study, the etch rates of AlN and Al1-xScxN with different scandium concentrations were investigated. The findings provide valuable insights for structure/composition analysis and potential applications.
Article
Physics, Applied
Jeffrey X. Zheng, Merrilyn Mercy Adzo Fiagbenu, Giovanni Esteves, Pariasadat Musavigharavi, Akhil Gunda, Deep Jariwala, Eric A. Stach, Roy H. Olsson
Summary: Ferroelectric Al1-xScxN is of interest for its unique ferroelectric properties and compatibility with metal oxide semiconductor back-end-of-line processing. However, for applications in embedded nonvolatile memory, a lower switching voltage is desired. This study demonstrates that reducing the thickness of Al0.72Sc0.28N films can decrease the coercive field and increase the breakdown field. A 5.4nm film showed ferroelectric switching at 5.5V and a switching speed of 60 ns when excited with a 500 ns pulse.
APPLIED PHYSICS LETTERS
(2023)
Article
Materials Science, Multidisciplinary
Eric Lang, Thomas Beechem, Anthony McDonald, Tom Friedmann, Roy H. Olsson, Jeffrey O. Stevens, Blythe G. Clark, Khalid Hattar
Summary: Ion implantation is commonly used in the fabrication of LiNbO3 devices, and the defects created by implantation can affect the properties of the material. This study systematically examined the effects of ion species, irradiation energy, implantation fluence, and post-irradiation heat treatment on defect formation in LiNbO3. It was found that suitable defect formation for fracture-based processes can be achieved with the implantation of He ions at a fluence of 1 x 1018 ions/cm2 and heat treatment at 250 or 500 degrees C.
Article
Physics, Applied
Seunguk Song, Kwan-Ho Kim, Srikrishna Chakravarthi, Zirun Han, Gwangwoo Kim, Kyung Yeol Ma, Hyeon Suk Shin, Roy H. Olsson, Deep Jariwala
Summary: This study presents a MoS2 negative capacitance FET based on AlScN ferroelectric material. By including a non-ferroelectric dielectric layer in the gate stack, the hysteresis behavior of the NCFET can be minimized, demonstrating excellent transport characteristics.
APPLIED PHYSICS LETTERS
(2023)
Article
Physics, Applied
L. Hackett, M. Miller, R. Beaucejour, C. M. Nordquist, J. C. Taylor, S. Santillan, R. H. Olsson, M. Eichenfield
Summary: Recent advances suggest that aluminum scandium nitride films on silicon could be used for quantum electromechanical applications. In this study, we fabricate and characterize microwave silicon phononic delay lines with transducers made of aluminum scandium nitride films on silicon. We achieve an electromechanical coupling coefficient of 2.7% and demonstrate a path to increase it to at least 8.5%, which would enhance transduction efficiency and reduce device size. The one-sided transduction efficiency is 10% at 5 GHz at room temperature, and there is potential to increase it further by modifying device design and operating at cryogenic temperatures.
APPLIED PHYSICS LETTERS
(2023)
Article
Engineering, Electrical & Electronic
Merrilyn M. A. Izhar, Merrilyn M. A. Fiagbenu, Pariasadat Musavigharavi, Xingyu Du, Jeff Leathersich, Craig Moe, Abhay A. Kochhar, Eric A. Stach, Ramakrishna H. Vetury, Roy H. Olsson
Summary: This letter presents a K-band bulk acoustic wave (BAW) resonator constructed from an Al0.72Sc0.28 N periodically poled piezoelectric film. The resonators exhibited dominant resonance responses around 20 GHz, approximately four times higher than the resonance frequencies of similar unpoled devices fabricated on the same wafer. Resonators with a quality factor (Q(p)) of 160 and an electromechanical coupling (k(t)(2)) of 8.23% were achieved. The figure of merits (defined as FoM(I) = k(t)(2) Q(p) and FoM(II) = f(p)FoM(I) x 10(-9)) of the resonator are 13.2 and 274 which are higher than most reported acoustic resonators operating at K-band (18 GHz to 27 GHz) or higher frequency. The experimental results suggest that periodically poled BAW resonators are promising for emerging RF filter and oscillator applications at K-band frequencies.
IEEE ELECTRON DEVICE LETTERS
(2023)
Article
Physics, Applied
Zichen Tang, Giovanni Esteves, Roy H. Olsson
Summary: This study demonstrates the ability to invert the polarity of sputtered aluminum scandium nitride thin films through post-fabrication processes. High domain spatial resolution is achieved using lithography techniques and wet etching. The relationship between electrode width, poling voltage, and domain growth is experimentally studied and statistically analyzed.
JOURNAL OF APPLIED PHYSICS
(2023)
Article
Chemistry, Analytical
Thomas Mion, Michael J. D'Agati, Sydney Sofronici, Konrad Bussmann, Margo Staruch, Jason L. Kost, Kevin Co, Roy H. Olsson III, Peter Finkel
Summary: Magnetoelectric-based magnetometers are attracting attention due to their ultra-low-power systems and high sensitivity. By optimizing the design and using appropriate materials, the performance of these sensors can be improved.
Proceedings Paper
Engineering, Electrical & Electronic
Gokulanand M. Iyer, Anne-Marie Zaccarin, Roy H. Olsson, Kevin T. Turner
Summary: This study develops a capacitive moisture sensor printed on a fully biodegradable paper substrate, which is improved by cellulose nanofibril infiltration. It has the potential to be used in IoT systems for precision agriculture, enabling more efficient use of water and fertilizers.