1. 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

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

3. My background: chasing the dream
Sep 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

4. Enlarging my horizons

5. A world top 1% University, ranked 3rd among the Physics Departments
in UK according to the Research Excellence Framework 2014 (

6. 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.

7. “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

8. “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

9. 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

10. 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

11. 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).

12. 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

13. 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

14. 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).

15. 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)

16. 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, (2016)

17. 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, (2016)
Conference talk:
MBE th International Conference (Montpellier): “Resonant Zener tunnelling via zero-dimensional states in a narrow gap In(AsN) diode”.
Poster presentation:

18. 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).

19. 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

20. 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).

21. 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)

22. 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…)

23. Thank you for your attention!
What next?