Diffusion injected light emitting diode

Lauri Riuttanen

Diffusion injected light emitting diode

Julkaisun otsikon käännös: Diffusiolla viritetty loistediodi

Lauri Riuttanen

Tutkimustuotos: Doctoral Thesis › Collection of Articles

Abstrakti

Valaistus kuluttaa merkittävän osan sähköenergiasta maailmanlaajuisesti. Valaistuksen hyötysuhteen parantaminen on siis yksi merkittävimmistä menetelmistä vähentää kasvihuonepäästöjä. Vaikka loistediodien (LEDs, engl. light emitting diodes) nopea kehitys ja niiden ylivoimainen hyötysuhde kilpaileviin teknologioihin on antanut LED:eille jalansijaa myös yleisvalaistuksessa, LED-teknologia tarvitsee vielä tutkimusta, jotta ne voisivat täydellisesti korvata vaihtoehtoiset teknologiat. Perinteinen LED perustuu kaksoisheteroliitokseen (DHJ, engl. double heterojunction), jossa aktiivinen alue on valmistettu p- ja n-tyyppiseksi seostettujen alueiden väliin. Kytkemällä jännite rakenteen yli elektronit ja aukot liikkuvat sähkökentän mukaisesti ajautumisvirtana seostetutuista alueista kohti aktiivista aluetta, jossa ne rekombinoituvat vapauttaen energiaa fotoneina. Varaustenkuljettajien syöttö on perinteisessä LED-rakenteessa tyypillisesti erittäin hyvä. Haasteita ilmenee uusissa, eksoottisissa LED-rakenteissa, jotka perustuvat lähellä pintaa oleviin nanorakenteisiin. Näissä tapauksissa DHJ:n valmistaminen on hankalaa ja varaustenkuljettajien syöttö on usein heikkoa. Tämä väitöskirja esittelee kokeellisia tutkimuksia uudesta diffuusioon perustuvasta LED-rakenteiden viritysmenetelmästä. Menetelmässä aktiivisen alueen ei tarvitse olla seostettujen alueiden välissä. Kokeelliset todisteet menetelmän toimivuudesta näytetään kahdella eri tyyppisellä prototyyppirakenteella. Ensimmäinen prototyyppi on pn-liitoksen alle haudattu monikvanttikaivorakenne. Toisessa prototyypissä yksittäinen kvanttikaivo on pn-liitoksen päällä. Ensimmäinen koerakenne osoitti, että pn-liitoksen ulkopuolelle valmistetun aktiivisen alueen viritys onnistuu. Toisella rakenteella havaittiin merkittävä hyötysuhteen parannus. Se myös osoitti, että pinnassa sijaitseva rakenne voidaan virittää sen alla olevalla pn-liitoksella. Mahdollisia sovelluksia menetelmälle löytyy jo mainittujen sovellusten lisäksi vihreiden puolijohdevalolähteiden valmituksessa sekä pii-teknologiaan integroitavissa valolähteissä.

Julkaisun otsikon käännös	Diffusiolla viritetty loistediodi
Alkuperäiskieli	Englanti
Pätevyys	Tohtorintutkinto
Myöntävä instituutio	Aalto-yliopisto
Valvoja/neuvonantaja	Sopanen, Markku, Vastuuprofessori Suihkonen, Sami, Ohjaaja
Kustantaja	Aalto University
Painoksen ISBN	978-952-60-6581-6
Sähköinen ISBN	978-952-60-6582-3
Tila	Julkaistu - 2015
OKM-julkaisutyyppi	G5 Tohtorinväitöskirja (artikkeli)

Tutkimusalat

galliunnitridi
III-nitridit
diffuusio

Pääsy asiakirjaan

http://urn.fi/URN:ISBN:978-952-60-6582-3Lisenssi: Määrittelemätön

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@phdthesis{2f0d8ac66af246c9aa8ad458d2721c84,

title = "Diffusion injected light emitting diode",

abstract = "Lighting plays a major role in consumption of electrical energy in the world. Thus, increasing the efficiency of light sources is one key element in reducing the green house gas emissions. Light emitting diodes (LEDs) are gaining a foothold in general lighting. Despite their rapid development in light output and their superior efficiency compared to other light sources, LEDs still need improvements in order to become the ultimate lighting technology. A typical LED is a double heterojunction (DHJ) structure, in which the active region fabricated from a lower band gap material is sandwiched between higher band gap p- and n-doped regions. By biasing such a structure electrons and holes are transferred by current into the active region, where they recombine releasing energy as photons. The carrier injection in a conventional LED structure is typically efficient. However, in more exotic novel structures based on nanowires or near surface nanostructures, fabricating a DHJ becomes difficult. This thesis presents the experimental studies on a novel current injection method for light emitting applications. The method is based on bipolar diffusion of charge carriers. Unlike in the conventional method, the active region does not have to placed between the p- and n-layers of the pn-junction. The diffusion injection method is experimentally demonstrated by two types of prototype structures. The first prototype was fabricated using a multi quantum well (MQW) stack buried under the pn-junction. The second prototype was fabricated using a near surface quantum well (QW) placed on top of the pn-junction. The first prototype showed that the diffusion current components can be used to excite an active region outside of the pn-junction. The second prototype showed a large improvement in injection efficiency as well as the suitability of the method for exciting surface structures. The applications of diffusion injection can be found in blue galliun nitride based LEDs studied in this thesis as well as in green solid-state light sources, light sources integrated into silicon technology and devices based on nanostructures and plasmonics.",

keywords = "gallium nitride, III-nitrides, LED, diffusion, galliunnitridi, III-nitridit, diffuusio, gallium nitride, III-nitrides, LED, diffusion",

author = "Lauri Riuttanen",

year = "2015",

language = "English",

isbn = "978-952-60-6581-6",

series = "Aalto University publication series DOCTORAL DISSERTATIONS",

publisher = "Aalto University",

number = "213",

address = "Finland",

school = "Aalto University",

}

TY - THES

T1 - Diffusion injected light emitting diode

AU - Riuttanen, Lauri

PY - 2015

Y1 - 2015

N2 - Lighting plays a major role in consumption of electrical energy in the world. Thus, increasing the efficiency of light sources is one key element in reducing the green house gas emissions. Light emitting diodes (LEDs) are gaining a foothold in general lighting. Despite their rapid development in light output and their superior efficiency compared to other light sources, LEDs still need improvements in order to become the ultimate lighting technology. A typical LED is a double heterojunction (DHJ) structure, in which the active region fabricated from a lower band gap material is sandwiched between higher band gap p- and n-doped regions. By biasing such a structure electrons and holes are transferred by current into the active region, where they recombine releasing energy as photons. The carrier injection in a conventional LED structure is typically efficient. However, in more exotic novel structures based on nanowires or near surface nanostructures, fabricating a DHJ becomes difficult. This thesis presents the experimental studies on a novel current injection method for light emitting applications. The method is based on bipolar diffusion of charge carriers. Unlike in the conventional method, the active region does not have to placed between the p- and n-layers of the pn-junction. The diffusion injection method is experimentally demonstrated by two types of prototype structures. The first prototype was fabricated using a multi quantum well (MQW) stack buried under the pn-junction. The second prototype was fabricated using a near surface quantum well (QW) placed on top of the pn-junction. The first prototype showed that the diffusion current components can be used to excite an active region outside of the pn-junction. The second prototype showed a large improvement in injection efficiency as well as the suitability of the method for exciting surface structures. The applications of diffusion injection can be found in blue galliun nitride based LEDs studied in this thesis as well as in green solid-state light sources, light sources integrated into silicon technology and devices based on nanostructures and plasmonics.

AB - Lighting plays a major role in consumption of electrical energy in the world. Thus, increasing the efficiency of light sources is one key element in reducing the green house gas emissions. Light emitting diodes (LEDs) are gaining a foothold in general lighting. Despite their rapid development in light output and their superior efficiency compared to other light sources, LEDs still need improvements in order to become the ultimate lighting technology. A typical LED is a double heterojunction (DHJ) structure, in which the active region fabricated from a lower band gap material is sandwiched between higher band gap p- and n-doped regions. By biasing such a structure electrons and holes are transferred by current into the active region, where they recombine releasing energy as photons. The carrier injection in a conventional LED structure is typically efficient. However, in more exotic novel structures based on nanowires or near surface nanostructures, fabricating a DHJ becomes difficult. This thesis presents the experimental studies on a novel current injection method for light emitting applications. The method is based on bipolar diffusion of charge carriers. Unlike in the conventional method, the active region does not have to placed between the p- and n-layers of the pn-junction. The diffusion injection method is experimentally demonstrated by two types of prototype structures. The first prototype was fabricated using a multi quantum well (MQW) stack buried under the pn-junction. The second prototype was fabricated using a near surface quantum well (QW) placed on top of the pn-junction. The first prototype showed that the diffusion current components can be used to excite an active region outside of the pn-junction. The second prototype showed a large improvement in injection efficiency as well as the suitability of the method for exciting surface structures. The applications of diffusion injection can be found in blue galliun nitride based LEDs studied in this thesis as well as in green solid-state light sources, light sources integrated into silicon technology and devices based on nanostructures and plasmonics.

KW - gallium nitride

KW - III-nitrides

KW - LED

KW - diffusion

KW - galliunnitridi

KW - III-nitridit

KW - diffuusio

KW - gallium nitride

KW - III-nitrides

KW - LED

KW - diffusion

M3 - Doctoral Thesis

SN - 978-952-60-6581-6

T3 - Aalto University publication series DOCTORAL DISSERTATIONS

PB - Aalto University

ER -

Diffusion injected light emitting diode

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