Aixtron (Germany)

This talk presents a summary on recent progress in Metal-Organic Chemical Vapor Deposition (MOCVD) technology to satisfy industrial and academic demand in epitaxial growth technology as well as the direct impact on device performance. We discuss notable advancements in MOCVD, including improved film quality, growth uniformity, impurity control, dislocation reduction, automation, and simulation. Key factors driving progress include novel advanced reactor designs, automated wafer handling, cleaning procedures to minimize particle density on wafer and optimized process parameters on even larger wafer as well as continuous stable operation of the system. As examples for new market opportunities wide band gap (GaO, GaN, SiC) power devices and the related technology aspects will be compared and discussed.

Precise fiber coupling and lens alignment are critical in modern photonic systems. AIXEMTEC GmbH has developed a modular construction kit tailored for automated fiber coupling and lens attach processes. This unified platform combines modular hardware, software, and process components to enable submicron precision and high flexibility. It supports both active and passive alignment strategies and accommodates single-mode and multi-mode fibers, micro-optics, and standard connectors. Through an intuitive user interface, users can configure automated sequences for positioning, dispensing, UV curing, and inspection—streamlining adaptation to new tasks. The system’s modularity accelerates development and reduces time-to-market for customized photonic devices. With pre-defined alignment algorithms and vision-based referencing, the platform ensures repeatable, high-yield results suitable for prototyping and industrial production. Example use cases highlight its efficiency and precision, making it ideal for transitioning from R&D to series production in photonic packaging applications across datacom, quantum, and sensing domains.

Engineered SiC wafers with a thin 4H-SiC layer bonded on a polycrystalline carrier substrate for the application as substrate in epitaxy are investigated. Epitaxial layers grown on such substrates in 150 mm and 200 mm diameter are compared to those on state-of-the-art conventional substrates from different vendors. The performance of the engineered wafers is judged by doping and thickness uniformities as well as the number and statistics of killer defects in the epitaxial layer.

Graphene is a gapless 2D material that could be used to fabricate superior electronic devices and circuits, particularly useful in the fields of telecommunication and sensing. While promising performance has been demonstrated at the laboratory scale, graphene integrated circuits at the wafer level suffer from poor reliability due to native defects, especially at interfaces with dielectrics and electrodes. Here, we show the fabrication of highly reliable graphene-based microchips, containing transistors and frequency doublers, on 200mm wafers through a multi-project wafer tape-out. Our transistors use multilayer hexagonal boron nitride (hBN) as gate dielectric, and they exhibit record performance in terms of reliability. In particular, our hBN/graphene transistors show ultra-low hysteresis below 20 mV and negligible shifts of the on-state current and the charge neutrality point even after 2100 cycles. The ultra-stable response of our hBN/graphene transistors contrasts with that of devices using metal-oxide gate dielectrics (HfO2, Al2O3), which exhibit severe degradation after a few dozens of cycles. These results, consistent across multiple devices, show low variability and demonstrate a scalable process for mass production of graphene-based microchips.

Organometallic complexes containing reactive alkali metals, such as lithium (Li), represent a promising material approach for electron injection layers and electron transport layers (EILs and ETLs) to enhance the performance of Organic Light-Emitting Diodes (OLEDs). 8-Quinolinolato Lithium (Liq) has shown remarkable potential as an EIL and ETL when conveyed in very thin films. Nevertheless, the deposition of nano-layers requires precise control over both thickness and morphology. In this work, we investigate the optical properties and morphological characteristics of Liq thin films deposited via Organic Vapor Phase Deposition (OVPD). Specifically, we present our methodology for analyzing the measured pseudodielectric function <ε(ω)> using Spectroscopic Ellipsometry (SE), alongside the nano-topography of evaporated Liq nano-layers using Atomic Force Microscopy (AFM). This information can contribute to the understanding of the functionality of this material, since ultra-thin Liq interlayers can significantly increase the operational stability of OLED architectures.

Fueled by the 5G revolution, the demand for advanced radio frequency micro-electromechanical systems (MEMS) based on AlScN is growing rapidly. However, synthesizing high-quality, textured AlScN thin films is challenging. Current approaches typically rely on high temperatures and expensive compound targets. In this study, we demonstrate the feasibility of ionized physical vapor deposition to deposit highly oriented AlScN films with minimal defects at lower temperatures. Using metal-ion synchronized high-power impulse magnetron co-sputtering (MIS-HiPIMS) we can selectively bombard the growing film with Al and/or Sc ions to enhance the adatom mobility while simultaneously providing the ability to tune stress and coat complex structures conformally. We find that the Sc solubility in wurtzite AlN is slightly reduced, whereas crystallinity and texture are markedly improved. Disoriented grains, a key challenge in growing AlScN films, are completely removed via substrate biasing, while the residual stress can be tailored by adjusting the same. The measured piezoelectric response of the films is in line with DFT predictions and on par with the current state of the art. Finally, we demonstrate conformal deposition of c-axis textured AlScN on structured Si wafers underlining the promise of ionized PVD for the fabrication of advanced RF filters and next-generation MEMS devices.

Abstract-This letter experimentally demonstrates 1.2 kV normally-off p-GaN gate lateral high-electronmobility transistors (HEMTs) on 200 mm diameter engineered substrates. The fabricated p-GaN gate HEMT with optimum gate-drain spacing exhibits a threshold voltage (Vth) of 3.2 V, an ON/OFF ratio of 108, low specific ON-resistance (Ron,sp) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$5.8 \mathrm{~m} \Omega-\mathrm{cm}^2$ </tex-math></inline-formula> and hard breakdown voltage (Vbd) at 1800 V. Optimized devices also show good wafer scale uniformity ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sigma_{\text {Ron }}=1.2 \%$ </tex-math></inline-formula> ) for the evaluated electrical parameters and passed on-wafer high temperature gate bias (HTGB) and reverse bias stress tests without device failures.

Heterostacks formed by combining two-dimensional materials show novel properties which are of great interest for new applications in electronics, photonics and even twistronics, the new emerging field born after the outstanding discoveries on twisted graphene. Here, we report the direct growth of tin nanosheets at the two-dimensional limit via molecular beam epitaxy on chemical vapor deposited graphene on Al2O3(0001). The mutual interaction between the tin nanosheets and graphene is evidenced by structural and chemical investigations. On the one hand, Raman spectroscopy indicates that graphene undergoes compressive strain after the tin growth, while no charge transfer is observed. On the other hand, chemical analysis shows that tin nanosheets interaction with sapphire is mediated by graphene avoiding the tin oxidation occurring in the direct growth on this substrate. Remarkably, optical measurements show that the absorption of tin nanosheets exhibits a graphene-like behavior with a strong absorption in the ultraviolet photon energy range, therein resulting in a different optical response compared to tin nanosheets on bare sapphire. The optical properties of ultra-thin tin films therefore represent an open and flexible playground for the absorption of light in a broad range of the electromagnetic spectrum and technologically relevant applications for photon harvesting and sensors.