PROMIS A Marie SkodowskaCurie Initial Training Network Postgraduate

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics WP 2 Characterisation of Novel Materials for Avalanche Photodiodes PROMIS Mid-term Review Meeting, London ESR : Shumithira Gandan Supervisors : Dr. Tomasz Ochalski & Dr. David Williams CIT @ Tyndall National Institute, Ireland 7 th December 2016

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Personal background • Beng (Hons) Electrical and Electronics Engineering, Malaysia • MSc Electrical and Electronics majoring in Photonics, Malaysia

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Project title Optical characterization of novel Avalanche Photodiode (APD) samples. Aim To obtain information from APD samples with various spectroscopy techniques such as photoluminescence (PL), time resolved photoluminescence (TRPL), modulation spectroscopy and spectral elipsometry Deliverables • Carrier dynamics and bandgap structure of the quartenary alloy. • Identification of possible defects and their activation energy to define the non-radiative recombination channels.

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Background of project Matter Photoluminescence Incident light ray Spectroscopy – Experimental techniques to measure the interaction of light with matter Transmission Absorption Electrical energy (laser) Reflection Energy Scattering Photonics – Physics of interaction of light with matter Samples tested -- Sample -Converts incident photons to different wavelength -- Filter -Passes part of the spectrum Novel quartenary materials for Avalanche Photodiodes Al. Ga. As. Sb --Detector--

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Photoluminescence spectroscopy Temperature dependent PL experiments for four samples of Al 1 -x. Gax. As. Sb, x = 0, 5, 10, 15 • Samples are placed in a cryostat and cooled to very low temperatures (7 -10 K) and heated slowly with measurements taken at each interval • Information: wavelengths at which radiative recombination occurs Wavelength (nm) • Intensity (a. u) Involves photoexcitation of the sample using a laser source so that the emission from the sample can be read and interpreted. Temperature (K)

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Intensity (a. u) Power dependence of Ga 15% at 7 K Wavelength (nm) Power dependent PL measurements are done to determine the most suitable power for sample excitation. Setup for PL and TRPL

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Time resolved photoluminescence spectroscopy Involves spectral and temporal evolution of the emission of a sample following its illumination by a short pulse of light. High Laserrepetition Laser rate Low

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics • • Intensity of emission proportional to the number of photo-generated carriers Information: transition energies, carrier lifetimes Decay times reflect recombination rates and reveals quality of crystalline structure Presence of impurities and defects significantly reduce decay times Wavelength(nm) Time(ps) Streak image of measured Al. Ga. As. Sb at 830 nm and 7 K Decay times of temperature dependent TRPL

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Photoreflectance & Electroreflectance spectroscopy • • A spectroscopy technique that allows probing of the electric field of the sample through electromodulation Information: bandgap structure and alloy composition particularly in quartenary compounds Setup for PR

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Collaboration with other WPs 1. WP 1 - Ga. As. N/Ga. As. N: H Quantum dots - Sapienza Universita’ di Roma 2. WP 3 - Ga. Sb. N Quantum dots in intermediate band semiconductors for solar cells - Lancaster University 3. WP 4 - In. As. Sb/Ga. Sb and plasmonics for high sensitivity chemical and bio -sensing - Universitè Montpellier 2 Ga. As: cap 100 nm Ga. As. N: H Ga. As. N QD stack (x 10) Ga. As: spacing Layer “ 0, 3, 5, 40 nm” Ga. Sb QD Ga. As: buffer Ga. Sb 100 nm n doping Ga. As (Si) substrate

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Summary • Different optical characterization techniques have been used to investigate the physical parameters and quality of the grown APD samples. • Continued characterization will provide a complete understanding of the Al 1 - x Gax As. Sb layers and allow feedback to University of Sheffield for optimizing growth of the sample layers for APD fabrication. • TRPL, PL and autocorrelation characterization of Ga. As. N/Ga. As. N: H quantum dot samples from Sapienza Universita’ di Roma was also done to provide feedback on quality of samples.

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Skills acquired • Advanced optical techniques in photoluminescence, time-resolved photoluminescence, and modulation spectroscopy • Ridge waveguide laser fabrication process • Cryogenics and vacuum technology • 2 week secondment in University of Sheffield; Ø Basic electrical characterization of avalanche photodiode samples, including IV, CV and X-ray absorption spectrum analysis. Ø Analysis of the rationale behind choosing specific parameters for the APD materials • Courses : Key Enabling Technologies (KETs) workshop, Photonic Devices and Materials, Advanced Characterization of Materials, Laser safety, Cryogenics safety training

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Outputs Poster presentation Effect of Gallium composition in Al. Ga. As. Sb alloys for APDs S. Gandan, J. S. D. Morales, X. Zhou, C. H. Tan, J. S. Ng and T. J. Ochalski, 19 th International Conference on Molecular Beam Epitaxy, Montpellier (2016) Oral presentation Optical characterization of natural and CVD diamonds and diamond nano-particles; emission dynamics studies Tomasz J. Ochalski, H. Ye, D. Saladukha, J. Morales, S. Gandan 33 rd International Conference on the Physics of Semiconductors, Beijing (2016) Optical spectroscopy of P-Ga. As nanopillars on Si for monolithically- integrated light sources J. S. D Morales, S. Gandan, D. Ren, D. L. Huffaker, T. J. Ochalski, SPIE, Photonics West Conference & Exhibition, San Francisco, California (Jan 2017)

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Future work • Numerical analysis of PR/ER spectra with Third Derivate Lineshape (TDLS) and Airy function line shape fitting to derive accurate bandgap information and broadening parameters of APD samples. • Spectroscopy and analysis of samples from collaborations. • Hosting of planned secondments ü 28 th November – 3 rd December 2016 ESR 14 from Universitè Montpellier 2 (Mario Bomers) ü Within the next month ESR 9 from Lancaster University (Denise Montesdeoca Cardenes) • Planned secondments ü Universitè Montpellier 2 (May 2017) ü University of Sheffield (2017)

PROMIS A Marie Skłodowska-Curie Initial Training Network Postgraduate Research on Dilute Metamorphic Nanostructures and Metamaterials in Semiconductor Photonics Aspirations • Industry position in photonics sector related to optical characterization techniques. • Academic position in a topic to further investigate physics related to spectroscopy.