Theoretical studies of optical transitions in semiconductor quantum structures

Osmo Vänskä

Theoretical studies of optical transitions in semiconductor quantum structures

Julkaisun otsikon käännös: Teoreettisia tarkasteluja puolijohteiden kvanttirakenteiden optisista transitioista

Osmo Vänskä

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Puolijohdemateriaaleista valmistetut nanorakenteet ovat funktionaalinen osa ledeissä, puoli-johdelasereissa ja elektroniikan komponenteissa. Rakenteiden pieni koko johtaa väistämättä siihen, että toiminnallisuuden mallintaminen ja ymmärtäminen edellyttää kvanttimaailman ilmiöiden tarkastelua. Optoelektronisten laitteiden teoreettisen tutkimuksen kannalta tämä tarkoittaa valon ja puolijohdemateriaalin välisen vuorovaikutuksen tutkimista. Tämä tutkimus lisää tietämystä siitä kuinka valo ja materia vuorovaikuttavat keskenään sekä mahdollistaa täysin uusien toiminnallisuuksien löytämisen. Väitöskirjassa luodaan uutta pohjaa kvanttirakenteissa esiintyvien ilmiöiden selittämiseen. Mielenkiinnon kohteena on ollut generoida teoreettinen kuvaus sellaisille optisen kentän ai-heuttamille ilmiöille, joissa puolijohteiden viritystiloissa nähdään muutoksia esimerkiksi liikemäärässä tai spatiaalisessa jakaumassa. Työssä tarkastellaan kahta rakennetyyppiä, kvant-tirenkaita ja -kaivoja. Kvanttirengas on toroidin muotoinen objekti, joka on tilavuudeltaan hyvin pieni. Toinen tarkasteltava systeemi on kaksoiskaivorakenne, jossa tyypillisen kvantti-kaivon sijasta onkin kaksi kaivoa yhden tunnelointikerroksen eri puolilla. Jälkimmäisessä rakenteessa yhdistyvät tyypin I ja tyypin II puolijohdeominaisuudet paikka-avaruudessa, jossa elektronit ja aukot voivat olla joko samassa tai vaihtoehtoisesti eri kaivossa. Tärkeimmät tulokset ovat kvanttirenkaiden tapauksessa löydetty valon emissiokulmasta riippuva fotoluminesenssi sekä kaksoiskaivorakenteen yhteydessä ennustettu eri kvasi-hiukkasten paikan koherentti kontrollointi selektiivisesti. Koska tulokset kvanttirenkaiden osalta ovat kiinteästi yhteydessä ratakulmaliikemäärän vaihtoon sähkömagneettisen kentän ja puolijohteen kvanttitilojen välillä, voivat saavutetut tulokset osoittautua merkittäviksi kvantti-informaatioteknologian eri osa-alueilla. Tämäntyyppisestä trendistä on paljon viitteitä kvanttioptiikan alalla. Kaivorakenteessa löydetty kvasihiukkasten kontrollointi saattaa merkitä suurta teknologista edistysaskelta, sillä hyödyntämällä tätä efektiä voidaan tutkia kulkeutumisprosesseja eri materiaalien välillä, joista erityisen mielenkiintoinen esimerkki on sellainen ilmiö, jossa kvanttikorrelaatiot siirtyvät rajapinnan yli vaikuttamatta hiukkasten sijaintiin.

Julkaisun otsikon käännös	Teoreettisia tarkasteluja puolijohteiden kvanttirakenteiden optisista transitioista
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Tittonen, Ilkka, Vastuuprofessori Kira, Mackillo, Ohjaaja, Ulkoinen henkilö
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6032-3
Sähköinen ISBN	978-952-60-6033-0
Tila	Julkaistu - 2014
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

puolijohteiden kvanttirakenteet
optiset transitiot
kvanttirengas
kaksoiskvanttikaivo
valon ratakulmaliikemäärä
puolijohdekvanttioptiikka
koherentti kontrollointi

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http://urn.fi/URN:ISBN:978-952-60-6033-0

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@phdthesis{5168232c89934e2493a44b18baf110dd,

title = "Theoretical studies of optical transitions in semiconductor quantum structures",

abstract = "Nanotechnologically fabricated structures out of compound semiconductor materials make up the functional parts in LEDs, in semiconductor lasers and in electronics components. The small size of the structures evidently leads to requiring the modeling to look at phenomena at the quantum level. Especially for optoelectronical devices, one needs to treat the interaction between light and semiconductor material. This research adds to the understanding of inter-pretations of light-matter interaction phenomena and makes it possible to find totally new and undiscovered functionalities in semiconductor nanostructures. This thesis presents work on modeling and creates new theoretical foundations for phenom-ena appearing in semiconductor quantum structures. Of special interest has been to generate a theoretical description to such phenomena that have been caused by an optical field and in which one sees changes, e.g., in angular momentum or spatial distribution of excited states. Basically, two kinds of structures are examined, quantum rings and wells. A quantum ring is a toroidal object of which volume is very small, but its diameter can be significant when com-pared to the wavelength of light. Another class of systems under study is a double quantum well structure, where there are two quantum wells on both sides of a tunnel barrier. In this system, the type-I and type-II semiconductor band-structure properties become combined in spatial coordinates, since the electrons and holes can occupy either the same or the separate quantum wells. The two most interesting results are the angle-of-emission dependent photoluminescence from the quantum rings and the coherent control of vertical transport of desired quasiparticles through material interfaces in the quantum-well system in a selective manner. Since the obtained results on quantum rings are closely connected to the orbital-angular-momentum coupling between light and matter, they can prove to be important in different quantum information schemes where this angular-momentum aspect of light has been found to be highly beneficial. In quantum optics, there already are visible trends towards this direction. The predicted coherent control in a double-quantum-well system may mean a large technological progress, since by utilizing this effect one can study transport properties between materials over an interface, one of the most interesting examples of such phenomena being the transfer of quantum correlations through the interface without changing the local densities of electrons.",

keywords = "semiconductor quantum structures, optical transitions, quantum ring, double quantum well, orbital angular momentum of light, semiconductor quantum optics, coherent control, puolijohteiden kvanttirakenteet, optiset transitiot, kvanttirengas, kaksoiskvanttikaivo, valon ratakulmaliikem{\"a}{\"a}r{\"a}, puolijohdekvanttioptiikka, koherentti kontrollointi, semiconductor quantum structures, optical transitions, quantum ring, double quantum well, orbital angular momentum of light, semiconductor quantum optics, coherent control",

author = "Osmo V{\"a}nsk{\"a}",

year = "2014",

language = "English",

isbn = "978-952-60-6032-3",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "214",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Theoretical studies of optical transitions in semiconductor quantum structures

AU - Vänskä, Osmo

PY - 2014

Y1 - 2014

N2 - Nanotechnologically fabricated structures out of compound semiconductor materials make up the functional parts in LEDs, in semiconductor lasers and in electronics components. The small size of the structures evidently leads to requiring the modeling to look at phenomena at the quantum level. Especially for optoelectronical devices, one needs to treat the interaction between light and semiconductor material. This research adds to the understanding of inter-pretations of light-matter interaction phenomena and makes it possible to find totally new and undiscovered functionalities in semiconductor nanostructures. This thesis presents work on modeling and creates new theoretical foundations for phenom-ena appearing in semiconductor quantum structures. Of special interest has been to generate a theoretical description to such phenomena that have been caused by an optical field and in which one sees changes, e.g., in angular momentum or spatial distribution of excited states. Basically, two kinds of structures are examined, quantum rings and wells. A quantum ring is a toroidal object of which volume is very small, but its diameter can be significant when com-pared to the wavelength of light. Another class of systems under study is a double quantum well structure, where there are two quantum wells on both sides of a tunnel barrier. In this system, the type-I and type-II semiconductor band-structure properties become combined in spatial coordinates, since the electrons and holes can occupy either the same or the separate quantum wells. The two most interesting results are the angle-of-emission dependent photoluminescence from the quantum rings and the coherent control of vertical transport of desired quasiparticles through material interfaces in the quantum-well system in a selective manner. Since the obtained results on quantum rings are closely connected to the orbital-angular-momentum coupling between light and matter, they can prove to be important in different quantum information schemes where this angular-momentum aspect of light has been found to be highly beneficial. In quantum optics, there already are visible trends towards this direction. The predicted coherent control in a double-quantum-well system may mean a large technological progress, since by utilizing this effect one can study transport properties between materials over an interface, one of the most interesting examples of such phenomena being the transfer of quantum correlations through the interface without changing the local densities of electrons.

AB - Nanotechnologically fabricated structures out of compound semiconductor materials make up the functional parts in LEDs, in semiconductor lasers and in electronics components. The small size of the structures evidently leads to requiring the modeling to look at phenomena at the quantum level. Especially for optoelectronical devices, one needs to treat the interaction between light and semiconductor material. This research adds to the understanding of inter-pretations of light-matter interaction phenomena and makes it possible to find totally new and undiscovered functionalities in semiconductor nanostructures. This thesis presents work on modeling and creates new theoretical foundations for phenom-ena appearing in semiconductor quantum structures. Of special interest has been to generate a theoretical description to such phenomena that have been caused by an optical field and in which one sees changes, e.g., in angular momentum or spatial distribution of excited states. Basically, two kinds of structures are examined, quantum rings and wells. A quantum ring is a toroidal object of which volume is very small, but its diameter can be significant when com-pared to the wavelength of light. Another class of systems under study is a double quantum well structure, where there are two quantum wells on both sides of a tunnel barrier. In this system, the type-I and type-II semiconductor band-structure properties become combined in spatial coordinates, since the electrons and holes can occupy either the same or the separate quantum wells. The two most interesting results are the angle-of-emission dependent photoluminescence from the quantum rings and the coherent control of vertical transport of desired quasiparticles through material interfaces in the quantum-well system in a selective manner. Since the obtained results on quantum rings are closely connected to the orbital-angular-momentum coupling between light and matter, they can prove to be important in different quantum information schemes where this angular-momentum aspect of light has been found to be highly beneficial. In quantum optics, there already are visible trends towards this direction. The predicted coherent control in a double-quantum-well system may mean a large technological progress, since by utilizing this effect one can study transport properties between materials over an interface, one of the most interesting examples of such phenomena being the transfer of quantum correlations through the interface without changing the local densities of electrons.

KW - semiconductor quantum structures

KW - optical transitions

KW - quantum ring

KW - double quantum well

KW - orbital angular momentum of light

KW - semiconductor quantum optics

KW - coherent control

KW - puolijohteiden kvanttirakenteet

KW - optiset transitiot

KW - kvanttirengas

KW - kaksoiskvanttikaivo

KW - valon ratakulmaliikemäärä

KW - puolijohdekvanttioptiikka

KW - koherentti kontrollointi

KW - semiconductor quantum structures

KW - optical transitions

KW - quantum ring

KW - double quantum well

KW - orbital angular momentum of light

KW - semiconductor quantum optics

KW - coherent control

M3 - Doctoral Thesis

SN - 978-952-60-6032-3

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Theoretical studies of optical transitions in semiconductor quantum structures

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