Davide Maria Di Paola (ESR15) London Heathrow 7th - 8th Dec 2016 Mid Term Review Report Davide Maria Di Paola (ESR15) London Heathrow 7th - 8th Dec 2016 “Electron Transport in Novel Mid-Infrared Materials and Devices” Supervisors: Prof A. Patanè, Dr O. Makarovsky

My background: chasing the dream Sep 2010 - Jul 2013: BSc at University of Trento “A comparison of flat and textured back-contact silicon photovoltaic cells” (Prof L. Pavesi) SICILY

My background: chasing the dream Sep 2013 - Oct 2015: MSc: University of Pisa on Condensed Matter Physics Jan - Sep 2015: MSc Thesis at Italian Institute of Technology (Genoa) “ Inkjet Printing of Two-dimensional Materials for Flexible Optoelectronics ” Prof A. Tredicucci – Dr F. Bonaccorso

Enlarging my horizons

A world top 1% University, ranked 3rd among the Physics Departments in UK according to the Research Excellence Framework 2014 (https://www.timeshighereducation.com/features/ref-2014-results-by-subject)

WP4: Materials for Environment Infrared (IR) photonics (λ > 700 nm) is currently used for thermal imaging. Still a lack of suitable (P > 1 mW) and cheap mid-infrared (MIR) components (λ = 2-5 μm). MIR photonics for gas sensing at target wavelengths: C-H (3.4 μm), HCl (3.55 μm), CO2 (4.0 μm), N2O (4.5 μm): air quality monitoring; car and industrial exhausts; detection at production facilities/disaster zones; pharmaceutical processing.

“Electron Transport in Novel Mid-infrared Materials and Devices” InAs: narrow bandgap Eg and low electron effective mass me* for high mobility & MIR applications InAs a Eg (T = 4.2 K) me* 6.058 Å 0.415 eV (λ ≈ 3.0 μm) 0.025 m0 a As In

“Electron Transport in Novel Mid-infrared Materials and Devices” Dilute nitride alloy InAs1-xNx: bandgap reduction via low N-incorporation (x < 5%) The bandgap reduction at different N-content can be modelled using a band anticrossing (BAC) model. (E. P. O’Reilly ey al.Trends in the electronic structure of dilute nitride alloys, Semicond. Sci. Technol. 24, 2009) InAs a Eg (T = 4.2 K) me* 6.058 Å 0.415 eV (λ ≈ 3.0 μm) 0.025 m0 InAs1-xNx a Eg (T = 4.2 K) me* 6.058 Å 0.38 eV (x = 1%) (λ ≈ 3.3 μm) 0.026 m0 a As In N

In(AsN) as active element in MIR devices resonant tunnelling diodes pn junctions and resonant tunnelling diodes (LEDs, lasers, photodiodes) In(AsN) active region p n i

p n i In(AsN) as active element in MIR devices pn junctions and resonant tunnelling diodes (LEDs, lasers, photodiodes) epilayers for Hall studies and plasmonics In(AsN) active region p n i Hybrid pn junctions for broad photoresponsivity photodiode

Training at Technical skills Research skills Safety regulations; Use of cryogenics, optical techniques, magnetic fields; Software for data analysis/modelling. Training at Research skills Paving the way to new findings by experiment and theory; Writing and reviewing literature; Dissemination of scientific results (posters, oral talks, journals).

Recent research highlights Novel structure to study the effect of N incorporation on transport properties: multi-layered In(AsN)-based p – i – n resonant tunnelling diode (RTD). NDR p i n 0D states

Recent research highlights Zener tunnelling via 0D states Electron tunnelling experiments in variable temperature and magnetic field enabled the observation of a novel type of Zener tunnelling via 0D states 0D states

Magneto-Tunnelling Spectroscopy (MTS) We exploit the effect of magnetic fields on electron tunnelling to map the wave function probability density |ψ|2 of the 0D states in k-space. Dk ~ B y0D k From B-dependence of the tunnelling current we infer strongly localized (~ 2 nm) N-related 0D states in In(AsN).

Outputs and Dissemination Publications: Resonant Zener tunnelling via zero-dimensional states in a narrow gap diode D.M. Di Paola, M. Kesaria, O. Makarovsky, A. Velichko, L. Eaves, N. Mori, A. Krier, A. Patanè Sci. Rep. 6 (2016)

Outputs and Dissemination Publications: Resonant Zener tunnelling via zero-dimensional states in a narrow gap diode D.M. Di Paola, M. Kesaria, O. Makarovsky, A. Velichko, L. Eaves, N. Mori, A. Krier, A. Patanè Sci. Rep. 6 (2016) Highly-mismatched InAs/InSe heterojunction diodes A. Velichko, Z. R. Kudrynskyi, D. M. Di Paola, O. Makarovsky, M. Kesaria, A. Krier, I. C. Sandall, C. H. Tan, Z.D. Kovalyuk, A. Patanè Appl. Phys. Lett. 109, 182115 (2016)

Outputs and Dissemination Publications: Resonant Zener tunnelling via zero-dimensional states in a narrow gap diode D.M. Di Paola, M. Kesaria, O. Makarovsky, A. Velichko, L. Eaves, N. Mori, A. Krier, A. Patanè Sci. Rep. 6 (2016) Highly-mismatched InAs/InSe heterojunction diodes A. Velichko, Z. R. Kudrynskyi, D. M. Di Paola, O. Makarovsky, M. Kesaria, A. Krier, I. C. Sandall, C. H. Tan, Z.D. Kovalyuk, A. Patanè Appl. Phys. Lett. 109, 182115 (2016) Conference talk: MBE 2016 - 19th International Conference (Montpellier): “Resonant Zener tunnelling via zero-dimensional states in a narrow gap In(AsN) diode”. Poster presentation:

Exchanges within the Network - March - April 2016: secondment on electroluminescence (EL) measurements; - Joint activity for our recent publication: Lancaster University: Marburg University: - High-resolution transmission electron microscopy (HR-TEM) to assess the material quality in In(AsN) resonant tunnelling diodes (RTDs). http://www.nature.com/articles/srep32039

Exchanges within the Network U. Montpellier: University of Rome: - June - July 2016: secondment on optical detection & modelling of plasmonic effects in InAsN:H epilayers; - Future plans (2017): surface patterning for plasmonic applications. - Future plans (2017): secondment on the hydrogenation of In(AsN). - Hydrogenation of In(AsN) epilayers for optical studies at UM2

Exchanges within the Network University of Sheffield: - Future plans (2017): secondment on the realization of devices (highly mismatched heterostructures of MIR alloys and van der Waals crystals).

Exchanges within the Network University of Sheffield Exchanges within the Network Lancaster University Electroluminescence Hybrid pn junctions Marburg University HR-TEM studies U. Montpellier Plasmonics in InAsN:H University of Rome Hydrogenation of In(AsN)

Research and Development Research in Academia i.e. post-doctoral position, fellowship, permanent position What next? Research and Development outside Academia (research-labs, companies…) Promoting Science (research councils, journals…)

Thank you for your attention! What next?