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Abstract

Mercury chalcogenide colloidal quantum dots based infrared photodetection has been intensely studied in the past few years and achieved background limited detectivity, sub-microsecond response time and much lower cost compared with the current leading technologies. To further improve their performances, new synthetic protocols need to be developed to tackle some of the current difficulties such as the control of doping-level and improvement in mobility and quantum yield. In this thesis, I focused on the synthetic efforts to obtain mercury chalcogenide quantum dots with better morphology and properties. For HgTe, non-aggregated HgTe quantum dots were synthesized for the first time and stabilized in the absence of thiols. HgTe/CdTe core/shells were then grown from these cores and showed much improved thermal stability. For HgSe, I used selenourea-derivatives to lower the precursor reactivity and obtained HgSe quantum dots with a better monodispersity around 6-7%. HgSe/CdX (X=S, Se, Te) core/shells were synthesized by both hot-injection and c-ALD methods and showed improved thermal stability and intraband PL quantum yield. The intraband PL quantum yield reached 10-3 at 5 µm. For HgS and HgS/CdS, a novel 2-phase method was used to provide an easy way of synthesizing these materials. The gradual transition from intraband to surface plasmon resonance was observed in HgS quantum dots and was explained by considering the local field effect. These methods open up possibilities to use these materials in current applications and new scenarios.

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