On Tuesday 25.02.2025, Timo Bißwanger successfully defended his PhD thesis. Congratulations to Dr. Timo Bißwanger on this fantastic accomplishment!

Christoph Stampfer had the opportunity to share more about our institute's experience with LLMs in physics teaching, especially with LandauAI (many thanks to Jan-Lucas Uslu) at the annual workshop of the "Studiendekan*innen" of RWTH Aachen University at Burg Obbendorf in Niederzier.

We warmly congratulate our former Bachelor’s and Master’s student, Jan-Lucas Uslu, on being admitted to the PhD program at the Department of Applied Physics at Stanford (California, USA). We a wish Jan-Lucas great success in his research and future endeavours!

As the festive season approaches quickly, we at the 2D Materials and Quantum Devices Group would like to extend our warmest wishes to all for a Merry Christmas and a Happy New Year 2025!

2D Materials 12, 015017 (2025)
We present a benchmarking protocol that combines the characterization of boron nitride (BN) crystals and films with the evaluation of the electronic properties of graphene on these substrates. Our study includes hBN crystals grown under different conditions (atmospheric pressure high temperature, high pressure high temperature, pressure controlled furnace) and scalable BN films deposited by either chemical or physical vapor deposition (CVD or PVD). We explore the complete process from boron nitride growth, over its optical characterization by time-resolved cathodoluminescence (TRCL), to the optical and electronic characterization of graphene by Raman spectroscopy after encapsulation and Hall bar processing. Within our benchmarking protocol we achieve a homogeneous electronic performance within each Hall bar device through a fast and reproducible processing routine. We find that a free exciton lifetime of 1 ns measured on as-grown hBN crystals by TRCL is sufficient to achieve high graphene room temperature charge carrier mobilities of 80,000 cm²/(Vs) at a carrier density of |n| = 10¹² cm^-2, while respective exciton lifetimes around 100 ps yield mobilities up to 30,000 cm²/(Vs). For scalable PVD-grown BN films, we measure carrier mobilities exceeding 10,000 cm²/(Vs) which correlates with a graphene Raman 2D peak linewidth of 22 cm^-1. Our work highlights the importance of the Raman 2D linewidth of graphene as a critical metric that effectively assesses the interface quality (i.e. surface roughness) to the BN substrate, which directly affects the charge carrier mobility of graphene. Graphene 2D linewidth analysis is suitable for all BN substrates and is particularly advantageous when TRCL or BN Raman spectroscopy cannot be applied to specific BN materials such as amorphous or thin films. This underlines the superior role of spatially-resolved spectroscopy in the evaluation of BN crystals and films for the use of high-mobility graphene devices.

Today, Bernd Beschoten from our group fascinated the audience with his "November-Vorlesung", i.e. talk on the world's shortest light pulses: femtoseconds and attoseconds. A truly inspiring journey through cutting-edge physics!