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Quantum-confined nanocrystals for infrared optoelectronics : carrier dynamics and intraband transitions

Abstract : Colloidal nanocrystals are crystalline objects grown by colloidal chemistry approaches. Thanks to quantum confinement, their optical properties depend on their size, and can then be tuned accordingly. Using mercury selenide and mercury telluride, we grow infrared-absorbing nanocrystals. While HgTe nanocrystals interband gap can be tuned from the NIR to the MWIR, HgSe nanocrystals display self-doping and intraband transitions in the MWIR to LWIR. With a careful control of their surface chemistry, those nanocrystals can be integrated into electrical devices to create cheap infrared photodetectors. In my PhD work, I am interested in probing carrier dynamics in those devices using various time-resolved techniques, either based on photocurrent measurements or on direct observation of the photocarriers relaxation. From dynamic study of HgSe intraband devices, I identify the issue brought by the degenerative doping level of those nanocrystals: transport is driven by the doping of this material, resulting in very poor IR-sensing performances. By taking inspiration from the III-V semiconductor developments, I propose several successful approaches to uncouple optical and transport properties in HgSe-based, MWIR detectors.
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Submitted on : Wednesday, September 30, 2020 - 6:31:10 PM
Last modification on : Friday, June 24, 2022 - 3:07:00 AM
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LIVACHE_Clement_2019.pdf
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  • HAL Id : tel-02954142, version 1

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Clément Livache. Quantum-confined nanocrystals for infrared optoelectronics : carrier dynamics and intraband transitions. Physics [physics]. Sorbonne Université, 2019. English. ⟨NNT : 2019SORUS216⟩. ⟨tel-02954142⟩

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