Laser writing on nanoscale-LEDs based on dilute nitrides. Mayank Shekhar Sharma PhD Student “La Sapienza” University of Rome.

Personal background history & achievements 5-Years Integrated M.Sc. in Photonics form CUSAT, India. Projects in nanophotonics, optical tweezing and photovoltaics. Internships in University of Hyderabad (India) and University of Duisburg-Essen (Germany) in 2013 and 2014 respectively. Master thesis in University of Gothenburg (Sweden) in 2015. Visiting researcher in Chalmers University of Technology (Sweden) for 3 months. Achievements: SPIE travel grant for presenting a research work on solar cells in the Annual Meeting of SPIE, San Diego, USA (2014). DST, INDIA scholarship for working on renewable sources of energy (nano-solar cells), (2013).

Aims & Deliverables To create site-controlled nanoscale light emitting spots or ordered LED arrays by laser writing using InGaAsN structures. (InGa)(AsN) p-i-n structures are grown in UMR and hydrogenated in ROME. Materials development will be targeted to key wavelengths in ICT, i.e. 1.31 μm and 1.55 μm.

Experimental techniques and/or concepts used Hydrogenation PL measurements Analysis Concepts: achieve full N passivation by H. fabrication of site-, size-, and shape-controlled nanostructures emitting at the desired wavelengths.

Background of project Photonics is important for information and communication technologies (ICT). Eg., fiber optics, internet. In ICT, photon sources are needed to be operated at 1.31μm and 1.51μm. Ultimate goal is produce reproducible nano-structuring techniques, and fabrication of nanoscale LEDs using them. Fabrication of nanoscale-LEDs based on laser-annealing of hydrogen irradiated (InGa)(AsN) will allow us to forward in this field.

Results & Analysis

InAsN vs. GaAsN: H role Hydrogen has more effect on GaAsN w.r.t. InAsN. InAsN/GaAs QW GaAsN/GaAs QW

What happens for intermediate cases? InGaAsN: Annealing effects Annealed InGaAsN/GaAs QW Not annealed InGaAsN/GaAs QW

Behavior of hydrogen

Summary Hydrogenation has finally shown a positive result which has to be undertaken as the first positive step towards passivation of nitrogen with a blue shift. In-N bonds causes inhibition of hydrogen effects. The reason might be the strain, cohesive energy, etc. which inhibits hydrogen to passivate nitrogen in indium rich samples.

Skills acquired Hydrogenation. Photoluminescence (Spectroscopic measurements). Optical table setup.

Outputs–publications, talks, posters, outreach Poster in MBE conference, Montpellier, September 2016.

Future work & aspirations Complete passivation of nitrogen in InGaAsN using hydrogenation. To fabricate nanoscale-LEDs based on laser-annealing of hydrogen irradiated (InGa)(AsN). Materials development will be targeted to key wavelengths, i.e. 1.31 μm and 1.55 μm.