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Ultrafast laser spectroscopy of semiconductor nanostructures
Neudert, Karel ; Trojánek, František (advisor) ; Nikl, Martin (referee) ; Herynková, Kateřina (referee)
This doctoral thesis deals with analysis of carrier dynamics in semiconductor nanocrystals and nanostructures by methods of ultrafast laser spectroscopy. In three chapters silicon, InAs/GaAs, InAs/AlAs and CdSSe materials are studied. Silicon nanocrystals prepared by sol-gel method were measured by time-resolved luminescence method with various time resolutions, two-photon absorption and Z-scan method. A model describing findings was suggested. InAs was well measured by upconversion method and gained knowledge appeared to be fully consistent with quantum model. CdSe material was examined in two basic forms - thin films of nanocrystals prepared by chemical deposition and nanocrystals in comercial filters. In both cases all questions regarding influencing optical properties of nanocrystals by modification of their growth were answered.
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Study of luminescence of semiconductor nanostructures accrued
Neudert, Karel
This diploma thesis deals with luminescence of silicon nanocrystals prepared by ion-implantation method. Samples have been characterized by time integrated spectroscopy. Time-resolved measurements were also done. We observed two-component photoluminescence with a great difference in decay times. Stretched-exponential decay of the slower one (s) was observed, described and compared to works of other authors. Great attention was paid to nonlinearities of the faster luminescence component ( 100ps) which were obtained by 532nm excitation. We suggested two-photon or two-step excitation model and new experiment to resolve this problem.
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Ultrafast laser spectroscopy of semiconductor nanostructures
Neudert, Karel ; Trojánek, František (advisor) ; Nikl, Martin (referee) ; Herynková, Kateřina (referee)
This doctoral thesis deals with analysis of carrier dynamics in semiconductor nanocrystals and nanostructures by methods of ultrafast laser spectroscopy. In three chapters silicon, InAs/GaAs, InAs/AlAs and CdSSe materials are studied. Silicon nanocrystals prepared by sol-gel method were measured by time-resolved luminescence method with various time resolutions, two-photon absorption and Z-scan method. A model describing findings was suggested. InAs was well measured by upconversion method and gained knowledge appeared to be fully consistent with quantum model. CdSe material was examined in two basic forms - thin films of nanocrystals prepared by chemical deposition and nanocrystals in comercial filters. In both cases all questions regarding influencing optical properties of nanocrystals by modification of their growth were answered.
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Study of luminescence of semiconductor nanostructures accrued
Neudert, Karel
This diploma thesis deals with luminescence of silicon nanocrystals prepared by ion-implantation method. Samples have been characterized by time integrated spectroscopy. Time-resolved measurements were also done. We observed two-component photoluminescence with a great difference in decay times. Stretched-exponential decay of the slower one (s) was observed, described and compared to works of other authors. Great attention was paid to nonlinearities of the faster luminescence component ( 100ps) which were obtained by 532nm excitation. We suggested two-photon or two-step excitation model and new experiment to resolve this problem.
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