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Embracing One Dimensional Semiconductor Nanostructures

Final Report Summary - NANOEMBRACE (Embracing One Dimensional Semiconductor Nanostructures)

One dimensional nanostructures (1DNS) of semiconductor materials are gaining much attention due to their unique physical properties and great potential for novel applications, e.g. ultra-compact LEDs and lasers, single photon emitters, solar cells, functional nano probes, sensors and nanoelectronic devices. The NanoEmbrace ITN brings together 10 leading academic institutions and 12 industrial partners to train 12 early stage researchers (ESRs) capable of solving the scientific tasks needed for the transition of 1DNS from laboratory to industry. Our main objectives were to gain a fundamental insight in the Physics underpinning reliable and controlled growth and to (ii) explore post-growth functionalisation of 1DNS. To achieve this, 4 core work programmes were implemented: (i) controllable growth of 1DNS; (ii) controlled modification of 1DNS composition to form quantum wire heterostructures; (iii) non-destructive characterisation of arrays of 1DNS and (iv) functionalisation and interfacing of as-grown 1DNS and batch processing.

Research: The main research achievements are very briefly summarised.

• Growth: We developed deterministic growth methods for obtaining ensembles of semiconductor nanowires (NWs) with predefined shape, dimensions, direction of growth, crystal structure, internal composition distribution (heterostructures) and position on a substrate. This implied coupling intimately growth proper and growth theory and modelling. We also explore the use of alternative substrates and catalysts for growing NWs. A broad domain was covered, ranging from the investigation and modelling of the fundamental mechanisms of NW growth to the fabrication of device-quality samples and exploring novel structures and growth procedures.

• Theory: Important progress in NW growth theory and modelling has been achieved. The knowledge and understanding generated can lead to more efficient development of optimal NW structures with pre-defined properties, including optoelectronic NW heterostructures and III-V NWs with pure crystal phase controlled by the growth parameter tuning, including polytypism. A comprehensive understanding of NW growth theory was developed for cost-effectiveness and to reduce the time consuming experimental trial and error approach.

• Characterisation: The size of NWs, tens of nm in diameter and a few μm in length, make the implementation of the characterisation methods (developed for the macro and microscale) an outstanding challenge for nanotechnology. Therefore, a strategy for non-destructive NW characterisation and the use of complementary techniques to achieve the most complete picture of the NW characteristics was developed. This included a multi-scale characterisation platform combining structural, electrical and optical characterisation to map individual and ensembles of NWs and resulting devices. This effort was supported by high resolution microscopy and advanced optical analysis, also utilised to characterise the processing techniques developed.

• Functionalisation: The objective of Functionalisation was to capitalise on the achievements in theory, growth and characterisation to demonstrate transformative new opportunities for the realisation of instruments, sensors, optoelectronic and energy conversion devices. The ambition was to exploit the unique properties of NWs to create practical opportunities that could not be achieved in any other way. We exploited the unique properties of NWs to demonstrate a number of devices: NW-enabled high sensitivity and high resolution scanning thermal microscopy, DNA-templated NWs organic vapour sensors; Polarisation control of LEDs; nanoscale porous silicon microtubes in an LED architecture; highly sensitive and wide dynamic range pressure sensors; LED and transmission devices and the components of a tandem solar cell.

• Training: Training of the ESRs was conducted at two different levels: the host university coordinated the day-to-day local training while NanoEmbrace provided network training to all ESRs, covering knowledge and intellectual abilities (Library and online resources, advanced specialised experimental techniques, advanced theoretical techniques for data analysis), Personal effectiveness (presentation skills, writing skills, project planning, reports writing, networking), research skills (research management, risk assessment in experiment, Chemical Safety) through 10 network training events detailed on the project website ( academic and industrial secondments. 4 ESRs have already completed their PhD while most of the rest are writing up.

• Networking: the interaction and networking within and outside the consortium was facilitated by the management structure (involving an ESRs) designed to maintain a close communication that ensured the delivery of the project objectives, to take corrective actions, apply contingency plans to address issues as they arise. A review of the overall progress of the network was held every 6 months, i.e. 9 management meetings took place where core decisions were collectively taken: organisation of training events and international conferences, the design of a project website ( maintained throughout and 2 years beyond the project, where major network activities and publications are posted on this web portal. An ESR platform by ESRs enabled them to maintain networking during and outside joint activities but also agree a joint strategy to deliver outreach.

• Outreach and Dissemination: The network website ( that is publicly accessible, provides ample information on publications, conferences, events organised, meetings and outreach activities. Our activities were actively promoted in mass media via YouTube, Facebook and LinkedIn. ESRs presented their projects and worked hard as Marie Curie Ambassadors by organising guided tours meetings for school and undergraduate students, participating in Café Scientifique, Young Entrepreneurs competition, Dragonfly outreach, Research Nights, Celebrate Science, Careers in Science, Engineering and RCUK Cutting Edge Science courses events, among others. NanoEmbrace partners gave tutorial, lectures, interviews and presented the consortium and our scientific achievements to the general public at International conferences, e.g. World Economic Forum 2015 and YouTube videos. 37 of the journal papers in high impact journals involved a direct contribution from ESRs who also contributed to 67 conference papers. The full set of papers published and invited lectures, including those for consortium members are reported on the project website.

• Final results and impacts: The scientific results achieved and summarised above are substantial and helped create a greater awareness of nanowire research and technologies. This is evidenced by the sheer number of external participants to our workshops and conferences. All ESRs enrolled on the project learnt the host country language which facilitated their social integration and knowledge of the local culture. The outreach activities conducted and the complementary skills training delivered enabled ESRs to confidently communicate science and their results to the general public and to a specialist audience. The cultural diversity and close interactions within the network enabled ESRs and project partners alike to raise their awareness of multicultural interactions and tolerance. It was an excellent vehicle for cross-fertilization. In terms of career prospects, about 7 of those ESRs who completed their PhD or are near completion have been offered a new employment contract within their host institution. The network has attracted new partners, including from Europe and as far as from China. The collaboration between partners has received new funding under H2020 to continue the collaboration. In all, the project was very successful in scientific research, cultural exchange and human interactions.