Research Interests

ULTRARAM™ is a novel, compound semiconductor, charge-storage memory that combines the speed and endurance of dynamic random access memory (DRAM) with the non-volatility of flash. With its extremely low switching energy, ULTRARAM™ is ultra-efficient, making it a strong candidate for so-called universal memory. At the core of ULTRARAM™ is a patented triple-barrier resonant tunnelling barrier that exploits quantum effects to allow it to switch from opaque to transparent to electrons on application of a small voltage. This gives ULTRARAM™ its contradictory property of being able to easily change robustly stored data.

Self-assembled GaSb quantum rings (QRs) are type-II compound semiconductor nanostructures that form a deep potential well for positive charge (holes) but expel electrons, such that they form a system analogous to an atom, with a positively-charged ‘nucleus’ to which electrons are electrostatically bound. After more than two decades studying the physics of GaSb QRs, current activities are focused on their exploitation in telecoms-wavelength LEDs, single photon LEDS

Research Overview

My research interests are in the physics and applications of low-dimensional semiconductor nanostructures (quantum wells, wires and dots). I collaborate with many UK and European universities, research institutes and companies.

Career Details

I studied at the University of Southampton and did a PhD and a postdoc at the University of Exeter, before moving to the European mainland. There I briefly worked in Paris, and then at the KU Leuven, Belgium for nearly 10 years, where I investigated semiconductor nanostructures in very high magnetic fields (up to 50 T). I returned to the UK to join the Physics Department in Lancaster in June 2006.

PhD Supervision Interests

Two projects are available. (1) Universal memory combines the best features of DRAM and flash, i.e. is non-volatile, low-voltage, non-destructively read, fast, cheap and high endurance. We recently demonstrated novel III-V compound semiconductor candidate universal memory cells (ULTRARAM), and research is rapidly progressing towards device scaling, fabrication of small arrays and implementation on Si substrates. The objective of this project is to develop and implement the III-V CMOS logic that will enable addressing of bits in large arrays (up to 1 Mbit). It will be suitable for someone with an interest in semiconductor device physics or electronic engineering. (2) VCSELs were recently used for 3D sensing in smartphones. 'Eye-safe’ VCSELs that emit above 1400 nm are preferred, but, all production VCSELs, including those in smartphones, lase below 1000 nm. The project will develop 1400 to 1600 nm VCSELs, based on our patented GaSb quantum ring technology.