Nanowire Quantum Dots for Novel Quantum Emitters

New EPSRC Grant awarded to Professor Huiyun Liu

Congratulations to UCL CDT Supervisor Professor Huiyun Liu, who has just been awarded a new 3.5 year EPSRC research grant worth almost £800k for his research proposal titled "GaAsP-GaAs nanowire quantum dots for novel quantum emitters" (EP/P000886/1). This is for a joint research project between Professsor Mowbray (Sheffield - EP/P000967/1) and Dr Ana Sanchez (Warwick - EP/P000916/1). The Sheffield, UCL and Warwick groups have a history of strong collaboration in the field of QD laser development and more recently nanowire growth and characterisation. The UK has international leading activities, both academic and industrial, in the fields of semiconductor nanotechnology, quantum information and data communications; all potentially impacted by this research project. The continued strength of these companies and academic groups depends on the development of improved and novel light emitters; the focus of this project. This highly interdisciplinary project will aim to achieve the ability to place these structures at pre-defined positions, offer greater control of the dot shape and size, and enable direct integration with a waveguide. This will overcome many of the disadvantages associated with self-assembled QDs and open up an increased range of applications harnessing the enhanced performance offered by these new devices with potential for significant impact on quantum technologies, solar cell technology, optoelectronics, ICT networks and distributed systems, non-CMOS device technology, photonic materials and metamaterials, and sensors and instrumentation.

This project will involve a comprehensive programme of III-V nanowire (NW) growth development, optical and structural characterisation and device development aimed towards the fabrication of novel silicon-based quantum light emitters based on GaAsP/GaAs NWQDs for silicon photonics. Professor Liu and his colleagues will aim to develop optically and electrically pumped Nanowire Quantum Dot (NWQD) lasers. III-V nanowire (NW) growth has been achieved previously via the vapour-liquid-solid (VLS) mode initiated by Au droplets. However, these introduce external contaminants which seriously degrade the electrical and optical properties of the NWs. More recently, self-catalysed (SC) III-V NWs have been intensively developed with growth initiated via the group-III element or in pre-defined holes in a surface mask; both approaches avoid contamination by external metals. By changing the composition during the nanowire growth it is possible to introduce one or more (up to 200 have been reported1) QDs within a nanowire, leading to the formation of nanowire quantum dots (NWQDs).

Professor Liu said:

"The fully quantised electronic states of zero-dimensional quantum dots permit the fabrication of both classical and non-classical highly efficient photon emitters, with significant advances for lasers and single photon sources."