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Modelling Dilute Nitride Semiconductors (PROMIS Mid-term Review Meeting)

This project focuses on the modelling of dilute nitride quantum wells and quantum dots to optimize their electronic and optical properties for opto-electronic applications. The software package S/PHI/nX is used for the calculations, and the Band Anti-Crossing model is employed to understand the electronic properties of nitride alloys. The research also includes the design and optimization of CPV solar cells and mid-IR LED structures. Skills acquired include Matlab and C coding, as well as proficiency in using S/PHI/nX.

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Modelling Dilute Nitride Semiconductors (PROMIS Mid-term Review Meeting)

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  1. Modelling Dilute Nitride Semiconductors (PROMIS Mid-term Review Meeting) Reza Arkani Supervisor: Eoin O’Reilly

  2. My specific background MSc in Photonics (Performance Enhancement of Thin-film Silicon Solar Cells Using Photonic Crystals) • BSc in Electrical Engineering • (Magneto-therapy) • Karaj University Laser & Plasma Research Institute

  3. My specific background I joined Tyndall National Institute on November 2015 to start my research in Photonics Theory Group. Demonstrating undergraduate module courses in Department of Physics, University College Cork

  4. My role in PROMIS project Modelling of dilute nitride quantum wells and quantum dots

  5. Dilute nitride semiconductors • In dilute nitride materials, localised Nitrogen resonant states reduce the band gap energy, and effectively cause the conduction band to split into two non-parabolic sub-bands leading to flexible wavelength tailoring. • Band Anti-Crossing (BAC) model provides a good basis to understand the electronic properties of nitride alloys. Dispersion relation for GaN0.005As0.995 calculated by BAC model Tomić, S., et al. , Physical Review B 69.24 (2004): 245305. Shan, w., et. al. , Physical Review Letters 82 (1999): 1221.

  6. Introduction to S/PHI/nX • S/PHI/nX • is a software package which uses continuum elasticity theory and multiband k.p model for opto-electronic properties of quantum nano-structures. • 2-band BAC: • for conduction band (CB) • 10-band BAC: • for valence band (VB) O. Marquardt, “Tutorial based on S/PHI/nX 2. 0. 2”, 2012 Gladysiewicz, M., et. al., Journal of Applied Physics 113.6 (2013): 063514.

  7. Quantum well calculation by 2-band & 10-band BAC model Bold lines: 2-band BAC Dashed lines: 10-band BAC Well width dependence of the transition energies of GaN0.02As0.98

  8. Simulation of strained QW structures InGaAsN GaAs Hydrostatic component Biaxial strain CB = 1.42 In0.35Ga0.65As0.98N0.02 GaAs GaAs CB = 1.14 CB = 1.04 δECBhy ΔEC = 0.29 e1 = 0.063 Energy (eV) Energy (eV) e1–hh1= 1.103 (1.13 μm) Eg = 1.42 VB = 0.11 HH = 0.10 δEVBhy ηaxhh VB = 0 ηaxlh LH = 0.08 hh1 = 0.006 ΔEV = 0.10 SO = -0.25 δEVBhy SO = -0.34 ηaxso SO = -0.27 Confinement potential for 8 nm wide In0.35Ga0.65As0.98N0.02/GaAs QW. Sketch of strain-related shifts in CB and VB of In0.35Ga0.65As0.98N0.02/GaAs.

  9. Simulation of Quantum Dots 6 nm 6 nm 6 nm Sketch of a GaN0.02As0.98/GaAs QD E = 1.24 eV E = 1.33 eV

  10. Summary • Studies on BAC model • Learning how to use S/PHI/nX as a powerful tool for quantum nano-structures calculations • QW band structure calculations using both 2-band & 10-band BAC model • QD band structure calculations using 2-band BAC model

  11. Skills acquired • Coding in Matlab and C • Application and use of freeware S/PHI/nX, including testing and learning how to deal with the bugs • Attended three courses in UCC: • Advanced Computational Physics • Advanced Condensed Matter Physics • Post-graduate Teaching & Demonstrating Module

  12. Outputs Poster presentation in Tyndall Poster Competition, July 2016 Poster presentation in the MBE Conference 2016 (as a part of PROMIS), September 2016

  13. Outlook Future works: • Optimising the electronic and optical properties of GaSbN QD’s for CPV solar cells grown by Lancaster University (WP3) • Designing and optimising the emission characteristics of Type-II InAsSbN/InAs/AlAsSb structures grown by Lancaster University for mid-IR LED applications (WP4) • Modelling hydrogenated dilute nitride semiconductors (WP1) Aspirations: • Industry/academic position in which I can use my knowledge, specifically optimisation studies in Photonics

  14. Thank you for your attention

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