2D sheets of atomically-thin materials have been intensively studied over the last few years, and have been found to bind together via van der Waals forces to create composites with unique optical and electronic properties. Here we report a study of the atomic structure and optoelectronic properties of some of the first examples of radial van der Waals heterostructures, where cylindrical sheets of different semiconductors (nanotubes) encase other materials. As described in our paper in Nano Letters, we found that BN overgrowth around carbon nanotube bundles created a good template for the creation of high-quality MoS2 nanotubes. This outer semiconducting wall had good electrical properties and strong optical absorption (including from the K-point excitons of MoS2), while the inner carbon nanotubes retained their excellent conductivity. This new class of composite may be suitable for unique functional optoelectronic devices on the nanoscale, such as 1D radial p-n junctions or transistors, for instance where the inner carbon nanotubes electrically control the outer semiconductor's conductivity.
PhD research studentships available
Please get in touch if you are interested in a PhD or MSc by Research in the group. We have two funded PhD studentships available for autumn 2020 start, titled Automation of THz imaging for Medical Diagnosis and An ultrafast shakedown of defects in diamond using intense infrared pulses. A number of other projects are suitable for motivated students looking to complete an MSc or a summer research project.
Congratulations Dr Mosley!
Many congratulations to Connor, who finished his PhD in style on the 11th December. Connor's work on "Enhanced Polarisation Control and Extreme Electric Fields: Advances in Terahertz Spectroscopy Applied to Anisotropic Materials and Magnetic Phase Transistions" has led to a new beamline at WCUS and a new type of terahertz radiation source.
Fantastic work, Connor, and best of luck for your next steps!
As part of the Warwick Christmas Lectures 2019 we held an optics-packed pre-show, featuring demos about some of the weird and wonderful properties of light. Members of the Physics Department and Ultrafast & THz group explained important phenomena like fluorescence, infrared light, polarisation and diffraction and more! The "twangs" of the Department's laser harp helped provide some festive music. There were 1100 members of the public at the lecture, a lot of whom made it to the pre-show science bonanza. On stage James talked about the power of lasers, ably assisted by Edward the Elf (below). Thanks to everyone who helped make the Christmas Lecture on 26th Nov such as success! More pictures here...
Photo © Michelle Tennison
Tera-fying castle trip
This year's spooky group social featured the tera-s of Warwick Castle at Halloween. Highlights included the bird show, battlement climb and delving into the dungeon.
Congratulations to Hannah on her first paper
Hannah's first paper presents "A Robust Protocol for In Vivo THz Skin Measurements" and has just appeared in J. Infrared MM THz - check it out here!
Over 900 physicists, chemists, engineers and biologists have descended on Paris for 1 week to discuss the latest science and technology in the infrared, mm-wave and terahertz bands of the spectrum. At IRMMW-THz 2019 the Warwick THz team, and Emma's team at CUHK, have 13 talks and posters, including Emma's plenary on THz instrumentation and analysis techniques for biomedical research, and Becky's keynote about Sn-containing hybrid perovskites for photovoltaics.
A triplet of THz talks
The summer conference season has started! Connor, Maurizio and Maria are presenting our recent work on THz polarisation control, carrier cooling in metal halide perovskites, and negative photoconductivity in carbon nanotubes over the next three weeks at Cleo Europe in Munich, Condensed Matter and Quantum Materials in St Andrews, and UK Semiconductors in Sheffield.
Welcome to Ziyi (Eric) Hu
A very warm welcome to Eric Hu, who has started his PhD on carbon nanotubes, supervised by Jeremy Sloan in Microscopy and James.