Low energy electron beam irradiation of gallium nitride

Henri Nykänen

Low energy electron beam irradiation of gallium nitride

Julkaisun otsikon käännös: Galliumnitridin säteilytys matalaenergisellä elektronisuihkulla

Henri Nykänen

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Tässä työssä on tutkittu galliumnitridin ja indiumgalliumnitridin käyttäytymistä kun niitä säteilytetään matalaenergisella elektronisuihkulla (engl., low energy electron beam irradiation, LEEBI). Tämän lisäksi tutkittiin ja valmistettiin periodisia hopearaidoituksia, jonka tavoitteena oli aikaansaada plasmonikytkentään perustuva valon emission lisäys. Sekä hopearaitojen, että LEEBI:n vaikutusta tutkittiin fotoluminesenssiin (engl., photoluminescence, PL) perustuvin mittauksin. Lisäksi hopearaitojen ominaisuuksia mitattiin käyttäen reflektometriaa. On osoitettu, että LEEBI aiheuttaa selvän vaimenemisen valon emission intensiteetissä metallo-orgaanisella kaasufaasiepitaksialla valmistetuissa InGaN kvanttikaivoissa (engl., quantum well, QW) sekä GaN-kalvoissa. Vaimeneminen on voimakkaampaa LEEBI-säteilyannoksen kasvaessa. Vaimeneminen on myös voimakkaampaa pienemmillä elektronien liike-energioilla. Tämä täsmää hyvin elektronisäteen energian tunkeutumisprofiilin kanssa. Vaimenemisen aiheuttavaa mekanismia on tutkittu positroniannihilaatiospektroskopialla (PAS). Mittaukset paljastavat, että LEEBI aktivoi valmistuksen aikana muodostuneita galliumvakansseja (VGa), jotka ovat muuten passiivisia. Toisin sanoen ne eivät vaikuta PL-signaaliin eivätkä näy PAS:ssa. Vakanssien passivaatiomekanismismi liittynee kompleksien muodostumiseen vedyn kanssa. Erityisesti VGa -3H kompleksi ei näy PAS-mittauksissa ja on neutraali. Koska vaimeneminen on identtistä näytteiden välillä, jotka on kasvatettu vedyssä ja typessä, voidaan todeta että vedyn lähde ei ole kantajakaasu. Näytteiden lämmittäminen palauttaa osan luminesenssin intensiteetistä. Todennäköisesti näytteen sisäinen vetydiffuusio uudelleenpassivoi vakansseja. Olemme kehittäneet pintarakenteen (poly)vinyyliakoholilla (PVA) peitetyistä hopeananoraidoista InGaN QW-rakenteen päälle. Hopearaidat voivat difraktoida valokanavamoodeja GaN- ja PVA-kerroksista, lisäten näin merkittävästi valon ulospääsyä rakenteesta. Tällä yksinkertaisella tekniikalla on saavutettu lähes 3-kertainen valon intensiteetti verrattuna käsittelemättömään näytteeseen.

Julkaisun otsikon käännös	Galliumnitridin säteilytys matalaenergisellä elektronisuihkulla
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Sopanen, Markku, Vastuuprofessori
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-5444-5
Sähköinen ISBN	978-952-60-5445-2
Tila	Julkaistu - 2013
OKM-julkaisutyyppi	G5 Artikkeliväitöskirja

Tutkimusalat

galliumnitridi
elektronisäteily
optinen laatu

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-5445-2

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@phdthesis{35da4ea5f2a9430a893dce3888de0d22,

title = "Low energy electron beam irradiation of gallium nitride",

abstract = "In this work, the behavior of gallium nitride and indium gallium nitride under low energy electron beam irradiation (LEEBI) has been investigated. Furthermore, a periodic silver grating has been investigated and fabricated with the aim of obtaining plasmonic coupling based luminescence enhancement from a light emitting structure. The effect of the silver grating and LEEBI were both studied using photoluminescence (PL) measurements and the silver grating properties were also investigated using reflectometry. It has been observed in this work that LEEBI causes significant degradation of band-edge (BE) luminescence in metal-organic vapor phase epitaxy (MOVPE) grown InGaN quantum well (QW) structures and GaN films. The degradation increases with increasing LEEBI dose (charge per surface area). Moreover, the PL intensity decreases faster with smaller kinetic energy of electrons. This in agreement with the electron beam energy dissipation profile in GaN. The mechanism of the BE luminescence degradation has been studied with positron annihilation spectroscopy (PAS). The measurements reveal that LEEBI is able to activate in-grown gallium vacancies (VGa) in GaN, which are otherwise passive, i.e., neutral through the band gap and invisible to PAS. The mechanism for the passivation of the VGa is the formation of vacancy - hydrogen complexes, especially VGa - 3H. Hence, LEEBI treatment can probably remove hydrogen from these complexes making them active. Moreover, LEEBI induced optical degradation was measured to be virtually identical for samples grown in both hydrogen and nitrogen environments. Also, a partial recovery of the BE emission was obtained with thermal annealing. This suggests internal migration of H, partially refilling the vacancy sites. A silver nano-grating structure covered with (poly)vinyl alcohol (PVA), deposited on top of an InGaN QW structure, was developed. The buried metal grating can diffract light from the optical modes propagating in GaN and PVA. This simple technique has already yielded emitted light intensity almost 3-fold the original.",

keywords = "gallium nitride, electron beam irradiation, optical degradation, galliumnitridi, elektronis{\"a}teily, optinen laatu, gallium nitride, electron beam irradiation, optical degradation",

author = "Henri Nyk{\"a}nen",

year = "2013",

language = "English",

isbn = "978-952-60-5444-5",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "190",

address = "Finland",

school = "Aalto University",

}

TY - BOOK

T1 - Low energy electron beam irradiation of gallium nitride

AU - Nykänen, Henri

PY - 2013

Y1 - 2013

N2 - In this work, the behavior of gallium nitride and indium gallium nitride under low energy electron beam irradiation (LEEBI) has been investigated. Furthermore, a periodic silver grating has been investigated and fabricated with the aim of obtaining plasmonic coupling based luminescence enhancement from a light emitting structure. The effect of the silver grating and LEEBI were both studied using photoluminescence (PL) measurements and the silver grating properties were also investigated using reflectometry. It has been observed in this work that LEEBI causes significant degradation of band-edge (BE) luminescence in metal-organic vapor phase epitaxy (MOVPE) grown InGaN quantum well (QW) structures and GaN films. The degradation increases with increasing LEEBI dose (charge per surface area). Moreover, the PL intensity decreases faster with smaller kinetic energy of electrons. This in agreement with the electron beam energy dissipation profile in GaN. The mechanism of the BE luminescence degradation has been studied with positron annihilation spectroscopy (PAS). The measurements reveal that LEEBI is able to activate in-grown gallium vacancies (VGa) in GaN, which are otherwise passive, i.e., neutral through the band gap and invisible to PAS. The mechanism for the passivation of the VGa is the formation of vacancy - hydrogen complexes, especially VGa - 3H. Hence, LEEBI treatment can probably remove hydrogen from these complexes making them active. Moreover, LEEBI induced optical degradation was measured to be virtually identical for samples grown in both hydrogen and nitrogen environments. Also, a partial recovery of the BE emission was obtained with thermal annealing. This suggests internal migration of H, partially refilling the vacancy sites. A silver nano-grating structure covered with (poly)vinyl alcohol (PVA), deposited on top of an InGaN QW structure, was developed. The buried metal grating can diffract light from the optical modes propagating in GaN and PVA. This simple technique has already yielded emitted light intensity almost 3-fold the original.

AB - In this work, the behavior of gallium nitride and indium gallium nitride under low energy electron beam irradiation (LEEBI) has been investigated. Furthermore, a periodic silver grating has been investigated and fabricated with the aim of obtaining plasmonic coupling based luminescence enhancement from a light emitting structure. The effect of the silver grating and LEEBI were both studied using photoluminescence (PL) measurements and the silver grating properties were also investigated using reflectometry. It has been observed in this work that LEEBI causes significant degradation of band-edge (BE) luminescence in metal-organic vapor phase epitaxy (MOVPE) grown InGaN quantum well (QW) structures and GaN films. The degradation increases with increasing LEEBI dose (charge per surface area). Moreover, the PL intensity decreases faster with smaller kinetic energy of electrons. This in agreement with the electron beam energy dissipation profile in GaN. The mechanism of the BE luminescence degradation has been studied with positron annihilation spectroscopy (PAS). The measurements reveal that LEEBI is able to activate in-grown gallium vacancies (VGa) in GaN, which are otherwise passive, i.e., neutral through the band gap and invisible to PAS. The mechanism for the passivation of the VGa is the formation of vacancy - hydrogen complexes, especially VGa - 3H. Hence, LEEBI treatment can probably remove hydrogen from these complexes making them active. Moreover, LEEBI induced optical degradation was measured to be virtually identical for samples grown in both hydrogen and nitrogen environments. Also, a partial recovery of the BE emission was obtained with thermal annealing. This suggests internal migration of H, partially refilling the vacancy sites. A silver nano-grating structure covered with (poly)vinyl alcohol (PVA), deposited on top of an InGaN QW structure, was developed. The buried metal grating can diffract light from the optical modes propagating in GaN and PVA. This simple technique has already yielded emitted light intensity almost 3-fold the original.

KW - gallium nitride

KW - electron beam irradiation

KW - optical degradation

KW - galliumnitridi

KW - elektronisäteily

KW - optinen laatu

KW - gallium nitride

KW - electron beam irradiation

KW - optical degradation

M3 - Doctoral Thesis

SN - 978-952-60-5444-5

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Low energy electron beam irradiation of gallium nitride

Abstrakti

Tutkimusalat

Pääsy asiakirjaan

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