一本道

Xe added as an inert diffusion additive during B鈧凜 CVD (from TEB) raises step coverage from 0.71 to 0.97 in 10:1 aspect ratio trenches, while preserving film composition and density. Conformal penetration is also achieved in lateral high-aspect-ratio features (≥50:1). A heavier background gas likely modifies precursor transport and promotes desorption of intermediates, providing a simple handle to tune conformality in demanding geometries.

Using a heavy inert diffusion additive for superconformal atomic layer deposition where Kr is added to the ALD process for AlN from TMA and NH₃ modifies the precursor distribution in recessed features and enhances film deposition at the bottom of the trenches. Step coverage in an 18:1 aspect ratio feature increased from 1 to 1.6. Five hundred ALD cycles render 24 nm at the top surface and 39 nm at the bottom of the trench. The heavier Kr promotes the diffusion of the lighter NH₃ down the trenches and could enhance the surface desorption which results in a lower GPC at the trench openings. XPS shows that the material quality is not changed when going deep inside the feature. The approach is applicable to many ALD processes.

Boron nitride is a promising two-dimensional material and a potential wide-bandgap semiconductor. CVD with organoboranes (TEB, TMB) yields h-BN that nucleates epitaxially (~4 nm) before a polytype transition to r-BN, evolving into less ordered turbostratic BN, or terminating by amorphous carbon. High resolution TEM and EELS show that carbon originating from the precursors deposits on the epitaxially growing h-BN surface and leads to polytype transition or complete surface poisoning with carbon terminating BN growth. The results question the use of organoboranes for CVD of high-quality epitaxial BN films and the polytype stability of h-BN on carbon-rich substrates such as graphene.

Two-dimensional carbides and nitrides (MXenes) offer tunable electronic, optical, mechanical, and electrochemical properties for applications including energy storage, electromagnetic interference shielding, wireless antennas, sensing, and medicine. Vapor phase synthesis is needed for integration on chips using current microfabrication device technology and large scale environmentally friendly synthesis methods are key for wide use in future additive manufacturing technologies. Discovery of new MXenes and combination with other materials in two dimensional heterostructures will enable new properties and expand use in flexible devices actuators optical lenses artificial memory devices and quantum computing.

Free-standing, one-atom-thick Au sheets produced from Au-intercalated MAX phases exhibit predicted graphene-like conductivity, strong flexibility, and corrosion resistance, enabling ultra-fine traces, stretchable interconnects, and drastically reduced Au consumption in electronics. Ongoing work targets wafer-size synthesis, property testing, and device fabrication.

Sub-nanometer control of multilayers improves performance of key neutron-optical elements. 鹿鹿B鈧凜 incorporation into Fe/Si multilayers enables higher reflectivity, improved polarization, reduced diffuse scattering, and lower roughness correlation. Adding 11B4C in Ni/Ti multilayers reduces interface widths from ~0.7 nm to ~0.3 nm and supports high-m waveguide designs. CrB鈧�/TiB岬� superlattices show single-crystal quality with ~monolayer interface widths, targeting high-reflectivity Fermi choppers. Low-temperature CVD yields fully conformal 10BxC at 450 掳C with B/C > 4 for solid-state neutron-detector concepts, supporting instrument layouts that deliver higher neutron flux to samples.

Single silicon vacancies and divacancies in 4H-/6H-SiC act as room-temperature spin qubits with long coherence times and optical addressability near telecom wavelengths. Charge-state control in p-i-n diodes, implantation into nanophotonic waveguides, and deterministic coupling to nearby nuclear spins enable initialization, coherent control, and entanglement of multi-spin registers. Wafer-scale material quality and mature nanofabrication provide a platform for quantum sensing and information devices based on stable color centers.

Ultrahigh-vacuum magnetron sputter epitaxy produces high-purity GaN and InAlN nanostructures. Straight, diameter-controlled nanorods, inclined and curved rods, nanochevrons, and chiral nanospirals. Diffusion-induced growth links rod length to inverse diameter and temperature, enabling geometry control for photonics, gas sensing, and high-power/optoelectronic devices. Arrays provide large junction area, low defect density, minimal substrate coupling, and periodic order for photonic engineering, including Fabry鈥揚茅rot-type nanocavity lasing and chiral nanophotonic responses.

Bioresponsive materials are designed to interact dynamically with their biological environment, enabling controlled therapeutic release and real-time diagnostic feedback. By integrating stimuli-responsive components, such as peptides, enzymes, or redox-active elements, into soft material matrices like hydrogels, nanocellulose, or liposomes, these systems can sense biochemical cues and respond through structural or functional changes. Such adaptive materials allow localized delivery of antimicrobial or anticancer agents, modulation of degradation and mechanical properties, and optical or colorimetric readouts of biological activity. This convergence of responsive chemistry, therapeutic functionality, and diagnostic capability defines a new generation of precision biomaterials for wound care, drug delivery, and regenerative medicine.

We are investigating two promising classes of materials鈥攐rganic semiconductors and metal halide perovskites鈥攖hat have the potential to revolutionize technologies such as solar panels, LED lighting, lasers, and sensors. Organic semiconductors are composed of carbon-based molecules. They are lightweight, flexible, and can be manufactured using straightforward, solution-based techniques. Metal halide perovskites, on the other hand, are crystalline materials known for their exceptional light absorption and efficient charge transport. These materials can be tuned to emit different colors and exhibit a remarkable tolerance to defects. While both material systems show great promise, several challenges remain. For example, we need improved methods for forming uniform thin films, minimizing defects, and enhancing stability under exposure to moisture, light, and electrical stress. Additionally, there is a growing emphasis on adopting environmentally sustainable fabrication approaches, developing scalable recycling strategies, and evaluating the full life cycle of these devices. Our research focuses on developing innovative strategies and deepening our understanding of these materials to address these challenges and advance device performance.