Please remember to apply for AVS Student National & Divisional Awards by May 10, 2023 11:59 PM EDT. If you are submitting an abstract to a session co-sponsored by a division or focus topic, you are still eligible to apply for that division's or focus topic's student award.

A total of eight national awards are given including: five (5) named awards and three (3) Graduate Research Awards for outstanding research by graduate student listed below. Please give this ADVISOR GUIDELINE (PDF) to your advisor. Your advisor will need to complete the required information online by the submission deadline. Please ensure that you give your advisor some extra time to complete the information on or before the deadline. No exceptions will be granted.

Numerous Divisional Awards in technical areas of interest to AVS are available. Students may apply for a National Student Award and one Division Group Award in a given year. If you are applying for a national award and divisional award, please make 2 separate applications - one for the national award and one for the divisional. See the requirements under the name of the Division Award.

Questions? Please contact Angela Klink, AVS Member Services Administrator, angela@avs.org

Authors: Jonas C. Gertsch, Jonathan L. Partridge, Austin M. Cano, Joel W. Clancey, Victor M. Bright, and Steven M. George

Publication: Thermal atomic layer etching of VO₂ using sequential BCl₃ and SF₄ exposures: Observation of conversion, ligand-exchange, and oxidation state changes

Journal of Vacuum Science & Technology A, Vol. 41, No. 1, Jan/Feb 2023

In the AVS Journal of Vacuum Science & Technology A, researchers from the University of Colorado Boulder explored the thermal ALE of vanadium oxide (VO₂) using sequential exposures of boron trichloride (BCl₃) and sulfur tetrafluoride (SF₄).

VO₂ is a room-temperature semiconductor with thermoresistive properties, so its resistivity and optical transmittance change as a function of temperature. This leads to potential applications in bolometers and smart windows, which conserve energy by becoming more reflective with increasing sunlight. The most effective implementations of the semiconductor require thin films that could be obtained using thermal ALE.

“Higher sensitivity is obtained for thinner VO₂ films because the heat is absorbed in a smaller volume,” said author Steven George. “We needed VO₂ ALE to fabricate the thin films for bolometers.”

The team explored the interactions between BCl₃, SF₄, and VO₂ during the etch process using Fourier transform infrared spectroscopy and quadrupole mass spectrometry. They determined the mechanisms and pathways for etching material as well as the rates and limiting factors for each reaction. They identified multiple pathways due to the range of possible reactions.

“BCl₃ is a versatile reactant that can undergo ligand-exchange with metal fluorides,” said George. “It also has the ability to convert metal oxides to B₂O₃ because B₂O₃ is a very stable metal oxide. This is important because B₂O₃ can be easily spontaneously etched using fluorination reactants like SF₄.”

They found that VO₂ thermal ALE occurred with BCl₃ participating in both ligand-exchange and conversion processes. They also observed oxidation reactions with SF₄. Using sequential exposures of both reactants, the team was able to employ and study each of these pathways during etching.

The authors plan to continue their work exploring additional materials and processes.

“My research group is working to develop thermal ALE for a wide spectrum of materials,” said George. “To this end, we are trying to develop a range of mechanisms. This will be valuable because isotropic etching is required for the fabrication of devices such as gate-all-around transistors and 3D NAND.”

Authors: Maximilian Liehr, Jubin Hazra, Karsten Beckmann, Vineetha Mukundan, Ioannis Alexandrou, Timothy Yeow, Joseph Race, Kandabara Tapily, Steven Consiglio, Santosh K. Kurinec, Alain C. Diebold, and Nathaniel Cady

Publication: Journal of Vacuum Science & Technology B, Vol. 41, 012805 (2023)

In this work, hafnium zirconium oxide (HZO)-based 100 × 100 nm² ferroelectric tunnel junction (FTJ) devices were implemented on a 300 mm wafer platform, using a baseline 65 nm CMOS process technology. FTJs consisting of TiN/HZO/TiN were integrated in between metal 1 (M1) and via 1 (V1) layers. Cross-sectional transmission electron microscopy and energy dispersive x-ray spectroscopy analysis confirmed the targeted thickness and composition of the FTJ film stack, while grazing incidence, in-plane x-ray diffraction analysis demonstrated the presence of orthorhombic phase Pca21 responsible for ferroelectric polarization observed in HZO films. Current measurement, as a function of voltage for both up- and down-polarization states, yielded a tunneling electroresistance (TER) ratio of 2.28. The device TER ratio and endurance behavior were further optimized by insertion of thin Al₂O₃ tunnel barrier layer between the bottom electrode (TiN) and ferroelectric switching layer (HZO) by tuning the band offset between HZO and TiN, facilitating on-state tunneling conduction and creating an additional barrier layer in off-state current conduction path. Investigation of current transport mechanism showed that the current in these FTJ devices is dominated by direct tunneling at low electric field (E < 0.4 MV/cm) and by Fowler–Nordheim (F–N) tunneling at high electric field (E > 0.4 MV/cm). The modified FTJ device stack (TiN/Al₂O₃/HZO/TiN) demonstrated an enhanced TER ratio of ∼5 (2.2× improvement) and endurance up to 10⁶ switching cycles. Write voltage and pulse width dependent trade-off characteristics between TER ratio and maximum endurance cycles (Nc) were established that enabled optimal balance of FTJ switching metrics. The FTJ memory cells also showed multi-level-cell characteristics, i.e., 2 bits/cell storage capability. Based on full 300 mm wafer statistics, a switching yield of >80% was achieved for fabricated FTJ devices demonstrating robustness of fabrication and programming approach used for FTJ performance optimization. The realization of CMOS-compatible nanoscale FTJ devices on 300 mm wafer platform demonstrates the promising potential of high-volume large-scale industrial implementation of FTJ devices for various nonvolatile memory applications.

Authors: Mohamed A. Abdelbar, James P. Ewen, Daniele Dini, Stefano Angioletti-Uberti

Publication: Polymer brushes for friction control: Contributions of molecular simulations

Biointerphases, Vol. 18, No. 1, January/February 2023

When polymer chains are densely grafted to solid surfaces, they form polymer brushes (PBs). The molecular configurations create an effective, low-friction lubrication method that is potentially useful for understanding and restoring human joints.

Because properties of PBs are difficult to directly study, computer simulations are used to model PB behavior. Researchers from Imperial College London investigated PB simulations and discussed their findings in the AVS journal Biointerphases. Abdelbar et al. provided a perspective on the advancements and gaps in simulating PB lubrication and the challenges of comparing models to experimental data.

PBs occur when polymer chains, end-grafted onto a substrate, are packed densely enough that steric excluded volume repulsion holds them perpendicular to the substrate. Polymer brush bilayers are the most common configuration; they provide lubrication to mammal synovial joints, including the human knee.

PBs are also fabricated to reduce friction in water-lubricated systems. As technology and understanding of PBs advance, manufactured PBs, like those with oleophilic properties, achieve lower friction and higher load-bearing capabilities.

To further improve PBs, computer simulations provide insight into qualities that are difficult to measure directly. However, computer models are limited in their ability to fully replicate the complex dynamics involved.

“Experiments serve as a direct lens into nature’s behavior and thus will always give physical results, given they are performed correctly,” said author Mohamed A. Abdelbar. “Comparing the results of simulations and experimental data allows us to ensure that our models and theoretical framework are grounded in physical reality.”

Instead of maintaining all the atomic structure and chemical detail, simulations often use a coarse-graining method that maintains only essential information. Coarse graining represents chemical monomers as beads which interact to form the polymer chain. This enables longer and larger simulations, but the limited detail returns results that are difficult to compare to experimental values. The Kremer-Grest bead-spring model is a simple, yet effective, coarse-graining model that others have built upon.

Thermostats control the temperature of such models and implicitly incorporate forces. As thermostat techniques improve, the authors recommend only applying the thermostat to the model’s confining walls, so the solvent does not artificially maintain a non-physical, constant temperature.

Computational limitations require simplified models of smaller chains on shorter time scales. The scale of computational simulations is often at least an order of magnitude smaller than PB experiments. And scale is not the only challenge when comparing simulated and experimental results. Unlike in models, in the lab, controlling properties like PB length, density, and stiffness is difficult.

As computational capabilities improve, so do simulations’ ability to provide insight into PBs and expand the vast applications of PBs.

“Molecular simulations are a great way of supplementing our theoretical understanding of such systems and providing access to unmeasurable quantities,” Abdelbar said.

Abdelbar is hopeful for future applications of PBs.

"Polymer brushes are showing great promise in restoring lubrication to degraded human cartilage, which could be crucial in the fight against osteoarthritis.”

Surface Science Spectra Special Topic Collection: Atomic Layer Deposition and Atomic Layer Etching

Surface Science Spectra (SSS) welcomes data submissions related to Atomic Layer Deposition (ALD) and Atomic Layer Etching (ALE) for publication in a Special Topic Collection planned in collaboration with the annual 23rd International Conference on Atomic Layer Deposition (ALD 2023) and the 10th International Atomic Layer Etching Workshop, taking place July 23-26, 2023 in Bellevue, Washington. This collection will include data presented during the annual meeting and workshop as well as other ALD and ALE data that was not presented at the conference but is submitted to the collection.

This collection is open to all techniques published in SSS, so consider submitting your XPS, AES, ToF-SIMS, SE, UV-vis, or LEIS data to the Special Topic Collection on ALD and ALE.

Upon acceptance in SSS, your data will be stored and available as a reference to researchers worldwide.

Submission requirements and templates can be found here.

Authors: R. Howl and I. Fuentes

Publication: AVS Quantum Sci. 5, 014402 (2023)

AVS Quantum Science (AQS):

Biointerphases:

Vincent S. Smentkowski, Senior Scientist, GE Vernova Advanced Research Center, will present a FREE AVS e-Talk on April 19, 2023 (1:00 p.m.-2:00 p.m. ET) on Surface Microscopy and Microanalysis in an Industrial Research Laboratory. Register for FREE by April 17, 2023

49th International Conference on Metallurgical Coatings & Thin Films (ICMCTF 2023)

The 49th International Conference on Metallurgical Coatings and Thin Films (ICMCTF 2023) is the premier international conference in the field of thin film deposition, characterization, and advanced surface engineering promoting global exchange of ideas and information among scientists, technologists, and manufacturers. Attendees from all over the world come to present their findings, exchange ideas, share insights, make new friends, and renew old acquaintances.

ICMCTF 2023 will include more than 90 high-profile invited speakers, in over 50 sessions, across fourteen technical and topical symposia. There will be several special interest talks and featured lectures, as well as focused topic sessions, short courses, an equipment exhibition, an awards program, and daily social networking events.

Plenary Lecture:

Li-Chyong Chen, Director, Center of Atomic Initiative for New Materials (AI-MAT), National Taiwan University, Taiwan, “Recent Trends in Artificial Photosynthesis: Atomistic / Surface Design and Probing of Nano-photocatalysts”

Exhibitors Keynote Lecture:

David Furrer, Senior Fellow, Discipline Lead, Materials & Processes Engineering, Pratt and Whitney, USA, “Future Requirements for Advanced Surface Modification and Coatings Technologies for Turbine Engine Applications”

Eight half-day short courses covering topics related to thin film deposition, characterization, and advanced surface engineering will be held during ICMCTF 2023 from Sunday-Thursday, May 21-25, 2023. All short courses will include detailed course notes and will run from 8:30 a.m.-12:30 p.m. or 1:30-5:30 p.m. Cost: $250 Regular and Student Attendees.

Equipment Exhibit:

The equipment exhibition is a great place to network and learn about new products, services, and application techniques that will help improve all facets of R&D, Engineering, Manufacturing, Quality Control, and general laboratory operations. Visit the exhibit hall for FREE (by registering as Exhibits Only) on Tuesday, May 23, from 12:00-7:00 p.m. and Wednesday, May 24, from 10:00 a.m.- 2:00 p.m. There are also discounted conference registration rates for those in the San Diego area.

For more information, please visit the conference website at https://icmctf2023.avs.org/.

The AVS 23rd International Conference on Atomic Layer Deposition (ALD 2023) featuring the 10th International Atomic Layer Etching Workshop (ALE 2023) will be a three-day meeting dedicated to the science and technology of atomic layer controlled deposition of thin films and atomic layer etching. Since 2001, the ALD conference has been held alternately in the United States, Europe and Asia, allowing fruitful exchange of ideas, know-how and practices between scientists.

The conference will take place Sunday, July 23-Wednesday, July 26, 2023, at the Hyatt Regency Bellevue in Bellevue, Washington (East Seattle). As in past conferences, the meeting will be preceded (Sunday, July 23) by one day of tutorials and a welcome reception. Sessions will take place (Monday-Wednesday, July 24-26) along with an industry tradeshow.

All presentations will be audio-recorded and provided to attendees following the conference (posters will be included as PDFs). Anticipated attendance is 800+.

The 16th International Conference on Mid-Infrared Optoelectronics: Materials and Devices (MIOMD 2023) will be held at the University of Oklahoma in Norman, Oklahoma on August 6-10, 2023 (Sunday -Thursday). The conference will bring together 100+ scientists and engineers from around the world to discuss recent progress and future trends in infrared optoelectronics. A wide range of topics including the following will be covered:

Ultra-wide bandgap materials have emerged as a potential route towards next generation power and RF devices with superior performance compared to conventional semiconductors such as Si, GaAs, SiC or GaN. Many of the figure-of-merits for predictive device performance scale non-linearly with increasing critical electric field which is directly related to increasing bandgap and show great promise for these materials. Gallium oxide (Ga2O3) is an UWBG material of particular interest due to the availability of high-quality, relatively inexpensive, large-area native substrates with a wide range of doping required for various applications. Despite tremendous advances in materials, device, and thermal management, there are many outstanding technical challenges that must be addressed in order to realize the full potential of Ga2O3. These include but are not limited to: epitaxial material quality and reductions of native defects; bulk substrate growth; advanced device scaling and fabrication processes; heterojunctions; thermal management; electrical and thermal co-design; and benchmarking circuit performance.

After a highly successful and widely attended in-person conference in Washington DC in August 2022, the 6th U.S. Workshop on Gallium Oxide (GOX 2023) will be held in the University at Buffalo Campus, Buffalo, New York on August 13-16, 2023. In this rapidly advancing field, this workshop provides a premier platform for reporting recent advances in materials, device, and circuit development and identify major scientific gaps. The intent is to create actionable coordination across government, industry, and academia to enable rapid transitional technologies in this field. There will be no written proceedings to facilitate a friendly and stimulating environment for scientific discussions among participants from domestic and international Ga2O3 research groups. Attendees can expect topics including, but not limited to: bulk and epitaxial growth, theory/modeling/simulations, device and circuit advancements, materials characterization and novel properties, thermal management, electro-thermal co-design and heterostructures.

GOX 2023 will consist of two and a half days of presentations by invited and contributed speakers, as well as two evening poster sessions where the latest Ga2O3 results can be discussed. The workshop will be preceded by a welcome reception beneficial for networking with others in the field and establishing new collaborations.

The 37th North American Conference on Molecular Beam Epitaxy (NAMBE 2023) is a prominent international forum for reporting scientific and technological developments in Molecular Beam Epitaxy research. The conference showcases important results from fundamental materials and device research, through technological applications, and into high-volume and low-cost production. NAMBE features the presentations of the MBE Innovator Award, the NAMBE Young Investigator Award, and the Best Student Paper awards.

The Workshop on Quantum Materials Epitaxy will be held September 16-17, 2023, at Monona Terrace. Watch for more details coming soon.