1. Eva Repiso Menendez
Growth and hydrogenation of Sb/N materials for high efficiency mid-IR LEDs in pollutant gas detection

2. Personal background
Bachelor in Physics
Oviedo University
4 months in Italian National Laboratory TASC
Project: Self-assisted n-type GaAs nanowires grown by MBE
M. Orru, E. Repiso et al.
Adv. Funct. Mater. 26, (2016)

3. Masters in Energies and Fuels for the future
Personal background
Masters in Energies and Fuels for the future
Autonoma Univeristy of Madrid
6 months part time in Crystal Growth Laboratory
Project: Simulation and growth in volume of CdZnTe single crystals
CrysMAS simulation of a Vertical Gradient Freeze furnace

4. WP 4 – Materials for environment. (Eva Lancs. , Mario Mont
WP 4 – Materials for environment (Eva Lancs., Mario Mont., Davide Nott.)
Growth and hydrogenation of Sb/N materials for high efficiency mid-IR LEDs in pollutant gas detection
Motivation for MIR LEDs gas detection
CH4, CO2, CO….
- environmental pollution monitoring
- optical gas sensing
- chemical process control
- medical diagnosis

5. Background – Mid-IR LEDs
Mid-IR LED output power
Background – Mid-IR LEDs
Main challenges
Auger, SRH non-radiative recombination
Optical extraction
Approaches
Sb nanostructures QW & QD
Dilute N
LED based CO2 gas sensor
GSS Ltd.

6. I-V, EL & PL Spectroscopy
Experimental Techniques – skills acquired
MBE growth
XRD & PL
Device Processing
I-V, EL & PL Spectroscopy
(4-300 K)
Modelling Nextnano
Top contact
Etching
Bottom contact
Mounting

7. InAsSb/InAlAs type-I MQW
Results
InAsSb/InAlAs type-I MQW
Band diagram at 0 K
Sample structure
I-V measurements of LEDs
Electroluminescence with temperature
CO2 absorption

8. InAsSb/InAlAs MQW Hydrogenated
Results
InAsSb/InAlAs MQW Hydrogenated
90 K Electroluminescence dependence on hydrogenation dose
300 K Electroluminescence dependence on hydrogenation dose
CO2 absorption
CO2 absorption

9. InAsSb/InAlAs MQW Hydrogenated
Results
InAsSb/InAlAs MQW Hydrogenated
90K Electroluminescence dependence on hydrogenation dose
Peak intensity
Peak wavelength

10. Results InSb/InAs type-II QDs InSb deposition time determines QDs size
InAs cap temperature influences size and intermixing
+ InAs cap
Mono Layers of QDs from XRD
InAs
InSb
QDs

11. Summary
LEDs grown containing strained InAs0.90Sb0.10 QWs
Characterisation shows EL up to RT
First hydrogenated mid-IR LEDs
PL samples grown containing InSb QDs
Shift in λ emission due to the cold cap
Work in progress
Effects of the cold cap on QDs morphology and defects
TEM at UCA (Atif Khan)
Hydrogenation at Sapienza University -Rome
Band engineering InAsSb/InAlAs enables better targeting the λ
Dilute N MBE

12. Skills acquired Device Characterization Processing
MBE growth III-V
Sample Characterization
XRD
Photoluminescence
Processing
Lithography
Thermal evaporator
Etching
Mounting and bonding
Device Characterization
I-V measurements
Electroluminescence
Power measurements
Nextnano modelling

13. 1st WebEx meeting (March 2016)
Outputs
Talks at Networks
1st WebEx meeting (March 2016)
Growth and hydrogenation of Sb/N materials for high efficiency mid-IR LEDs in pollutant gas detection
Speaker: Eva Repiso
b) Talk at PROMIS conference (Cadiz, April 2016)
InSb QDs for high efficiency mid-IR LEDs
Posters
a) 19th International MBE conference (Montpellier, Sept. 2016)
InSb QDs for mid-IR LEDs
Authors: E. Repiso, P. J. Carrington, A. Marshall, Q. Lu and A.Krier
Outreach
Webcast on Photonics
Day of Photonics, photos through Twitter

14. Future aspirations
Publish high impact papers;
Present talks at international conferences;
Mirsens 4th (May 2017)
UK semiconductors (June 2017)
SPIE optics+photonics (August 2018)
20th International MBE conference (Sept 2018)
Postdoc
Fellowship application
Academic/Industry career