Colloidal synthesis and doping of semiconductor nanocrystals
Akgül, Mehmet Zafer
Demir, Hilmi Volkan
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Colloidal semiconductor nanocrystals have drawn great interest for application areas in photonics and optoelectronics thanks to their superior optical properties including strong bandgap emission and tunability. Also, their suitability for solution-based processing has made them highly attractive for low-cost production of light-emitting diodes and lasers. Our objective in this thesis is to show the potential and versatility of semiconductor nanocrystals via colloidal synthesis and post-processing methods. The thesis work includes the synthesis of colloidal quantum dot and well structures and their post-doping and investigates their exciton decay dynamics. In this thesis a novel colloidal approach for the doping of zinc blende colloidal quantum wells was proposed and demonstrated for the first time. This new doping method uniquely relies on atomic layer deposition (ALD) process. Here we achieved the worlds first manganese-doped CdSe@CdS core@shell nanoplatelets using our technique of ALD-assisted doping. Also, we studied silver-doped CdTe quantum dots under different conditions. Our experimental work proved that the quantum yield enhancement of silver-doped CdTe quantum dots is a strong function of the nanocrystal size and doping concentration. Tuning the nanocrystal size and doping level, our aqueous core-only CdTe nanocrystals reached a record high photoluminescence quantum efficiency of 68%. For these quantum dots, various decay kinetics were proposed and the enhancement in the quantum yield was attributed to the trap state annihilation. The methods and results provided in this thesis contribute to the fundamental understanding of semiconductornanocrystals and pave the way for high-performance colloidal platforms and devices.
Colloidal quantum dots
Colloidal quantum wells
Colloidal atomic layer deposition (ALD)
Colloidal ALD-assisted doping
Embargo Lift Date2017-07-01
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Güzeltürk, Burak (Bilkent University, 2016-05)Owing to the tremendous progress in the past decade, semiconductor nanocrystals that are grown by low-temperature solution-phase epitaxy have evolved into highly promising material systems for optoelectronics with ever ...
Bose S.; Delikanli S.; Yeltik A.; Sharma M.; Erdem O.; Dang C.; Fan W.; Zhang D.H.; Demir H.V. (Institute of Electrical and Electronics Engineers Inc., 2017)We demonstrate high quantum yield broad photoluminescence emission of ultrathin sub-nanometer CdSe nanoplatelets (two-monolayer). They also exhibit polarization-characterized lateral size dependent anomalous heavy hole and ...
Petrou, A.; Scrace, T. A.; Murphy, J. R.; Zhang, P.; Norden, T.; Zhang, T.; Thomay, T.; Cartwright, A. N.; Delikanli S.; Akgul, M. Z.; Demir, H. V. (S P I E - International Society for Optical Engineering, 2016)We studied the photoluminescence (PL)) from CdSe/CdMnS/CdS core/multi-shell colloidal nanoplatelets, a versatile platform to study the interplay of optical properties and nanomagnetism. The photoluminescence (PL) exhibits ...