Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Impact of metastable defect structures on carrier recombination in semiconductors

Impact of metastable defect structures on carrier recombination in semiconductors

Presentation given to the 3D Materials Lab group in the Colorado School of Mines, led by Prashun Gorai https://www.prashungorai.org/, focused on our recent publication Impact of metastable defect structures on carrier recombination in semiconductors (https://doi.org/10.1039/D2FD00043A)

Also discussed are our recent papers:
https://pubs.acs.org/doi/abs/10.1021/acsenergylett.1c00380
https://www.sciencedirect.com/science/article/pii/S2590238521002733

For other research articles and updates, check out my website at:
https://seankavanagh.com/

Seán R. Kavanagh

April 19, 2022
Tweet

More Decks by Seán R. Kavanagh

Other Decks in Research

Transcript

  1. Impact of metastable defect
    structures on carrier recombination
    in semiconductors
    Seán R. Kavanagh
    Colorado School of Mines,
    15th Apr 2022
    Profs: Aron Walsh (Imperial) & David
    Scanlon (UCL)
    [email protected]
    e- / h+
    Dq
    D*q
    Dq±1

    View Slide

  2. Impact of metastable defect
    structures on carrier recombination
    in semiconductors
    Seán R. Kavanagh
    Colorado School of Mines,
    15th Apr 2022
    Profs: Aron Walsh (Imperial) & David
    Scanlon (UCL)
    [email protected]
    e- / h+
    Dq
    D*q
    Dq±1

    View Slide

  3. A Little Bit About Me
    • Undergraduate: Nanoscience, Physics &
    Chemistry of Advanced Materials at Trinity
    College Dublin, Ireland.
    • PhD: Modelling Solid-State Photovoltaic
    Materials, with an emphasis on defects and
    disorder, at Imperial College London &
    University College London.
    • 🥾🏔🏃🏋🏂🎥🍻☕🍕🍱🕺

    View Slide

  4. Defects: Flash Introduction
    4
    𝐺 = 𝐻 − 𝑇𝑆
    𝑐!
    = 𝑔exp
    −Δ𝐻
    𝑘"
    𝑇

    View Slide

  5. Motivation
    5

    View Slide

  6. Example: VCd
    0 in CdTe
    I. Mosquera-Lois and S. R. Kavanagh, Matter, 2021, 4, 2602–2605.

    View Slide

  7. Motivation
    7
    I. Mosquera-Lois and S. R. Kavanagh, Matter, 2021, 4, 2602–2605.

    View Slide

  8. Defect Dynamics
    • Alkauskas et al., Role of Excited States in
    SRH Recombination in Wide-Band-Gap
    Semiconductors, Phys. Rev. B, 2016. (LED
    Efficiency in GaN)
    • L.W. Wang, S.H. Wei et al., Non-Radiative
    Carrier Recombination Enhanced by Two-
    Level Process, Scientific Reports, 2016.
    (Solar Efficiency in CdTe; TeCd
    )
    • Guo et al., Nonradiative Carrier
    Recombination Enhanced by Vacancy
    Defects in Ionic II-VI Semiconductors,
    Phys. Rev. Applied, 2021. (Vse
    in ZnSe)
    S. R. Kavanagh, Aron Walsh and D. O. Scanlon, Rapid Recombination by Cadmium
    Vacancies in CdTe, ACS Energy Lett. 2021, 6, 4, 1392–1398

    View Slide

  9. Potential Structural Transitions
    Degenerate Minima: Thermal Excitation:
    Thermal Relaxation: Photo Excitation:
    E
    Q
    e- / h+
    e- / h+
    e- / h+

    View Slide

  10. 10
    a. Graph network of potential recombination pathways
    b. Standard electron-hole recombination
    c. Capture into metastable, relax, capture back
    d. Excite to metastable, capture, capture
    e. Excite, capture, relax, capture

    View Slide

  11. 11

    View Slide

  12. Case Study: Tei
    in CdTe
    12

    View Slide

  13. 13
    Case Study: Tei
    in CdTe

    View Slide

  14. 14
    Upper
    Orange
    Middle
    Blue
    Lower
    Orange
    e–
    h+

    View Slide

  15. 15
    h+ capture
    e– capture
    h+ capture
    e– capture
    h+ capture
    e– capture
    h+ capture
    e– capture
    Upper
    Orange
    Middle
    Blue
    Lower
    Orange
    e–
    h+

    View Slide

  16. 16

    View Slide

  17. CdTe: Tei
    Recombination Kinetics
    17

    View Slide

  18. Conclusions
    Defect dynamics can be crucial for
    understanding their impact on device
    performance.
    -> Demonstrated by Tei
    , where metastability
    catalyses a 4-step recombination cycle.
    Metastable defect structures potentially more
    important to non-radiative recombination than
    currently understood, particularly with:
    - Emerging ionic-covalent inorganic materials
    - Highly mobile defects
    Thanks to MPIE for the ‘Max Planck Travel
    Award’!
    Kavanagh, S. R.; Scanlon, D. O.; Walsh, A.; Freysoldt, C.
    Faraday Discuss. 2022.
    https://doi.org/10.1039/D2FD00043A.

    View Slide