Ändra sökning
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Influence of base-region thickness on the performance of Pnp transistor-VCSEL
KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
KTH, Skolan för informations- och kommunikationsteknik (ICT), Integrerade komponenter och kretsar.
Visa övriga samt affilieringar
2014 (Engelska)Ingår i: Optics Express, ISSN 1094-4087, E-ISSN 1094-4087, Vol. 22, nr 22, s. 27398-27414Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

We have recently reported a 980nm GaAs-based three terminal Pnp transistor-vertical-cavity surface-emitting laser (TVCSEL) operating at room temperature with optical power up to 1.8mW. However, the current gain beta = Delta I-c/Delta I-b was near zero just before lasing and became negative after the lasing threshold. The main cause of the negative current gain was found to be a gradual and position-dependent forward-biasing (saturation) of the base-collector junction with increasing bias even before lasing threshold. In this article, detailed multi-physics device simulations are performed to better understand the device physics, and find ways to avoid the premature saturation of the base-collector junction. We have optimized the thickness of the base region as well as its doping concentration and the location of the quantum wells to ensure that the T-VCSEL is in the active mode throughout its range of operation. That is, the emitter-base junction is forward biased and base-collector junction is reversed biased for sweeping the excess charges out of the base region.

Ort, förlag, år, upplaga, sidor
2014. Vol. 22, nr 22, s. 27398-27414
Nyckelord [en]
Surface-Emitting Laser, Bipolar-Transistor, Operation
Nationell ämneskategori
Elektroteknik och elektronik
Identifikatorer
URN: urn:nbn:se:kth:diva-156833DOI: 10.1364/OE.22.027398ISI: 000344004900093Scopus ID: 2-s2.0-84919969277OAI: oai:DiVA.org:kth-156833DiVA, id: diva2:768020
Forskningsfinansiär
Vetenskapsrådet, 2010-4386
Anmärkning

QC 20141203

Tillgänglig från: 2014-12-02 Skapad: 2014-12-02 Senast uppdaterad: 2017-12-05Bibliografiskt granskad
Ingår i avhandling
1. GaAs based Vertical-Cavity Surface-Emitting Transistor-Lasers
Öppna denna publikation i ny flik eller fönster >>GaAs based Vertical-Cavity Surface-Emitting Transistor-Lasers
2014 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

The ever-increasing demand for broadband capacity of the global optical communication networks puts enormous requirements on the semiconductor laser used in the optical transmitter. Industrial standard bodies for optical communication project requirements of single-channel data rates as high as 100 Gbit/s around year 2020. This is a significant step with respect to today's technology which is only at the verge of introducing 25 Gbit/s emitters. The preferred light source for these applications is the vertical-cavity surface-emitting laser (VCSEL) which can offer cost- and power-efficient directly modulated operation. However, it has proven extremely difficult to push the modulation bandwidth of VCSELs beyond 30 GHz and radically new device concepts are demanded to meet the upcoming needs. One such new device paradigm consists of the transistor laser which is the fusion of a semiconductor laser and a high-speed heterojunction bipolar transistor (HBT) into a single device, with potential significant advantages in modulation bandwidth, noise properties and novel functionality by virtue of the three-terminal configuration. The present thesis deals with the design, fabrication and analysis of vertical-cavity surface-emitting transistor-lasers (T-VCSELs), a device previously not realized or investigated in great detail.

GaAs-based T-VCSELs are investigated both theoretically and experimentally. A three-dimensional model is set up with a commercial software package and used for performance predictions and analysis as well as design and optimization purposes. It is concluded that a T-VCSEL biased in the common-base configuration may have a bandwidth surpassing those of conventional diode-type VCSELs or a T-VCSEL itself in the common-emitter configuration. Fabricated T-VCSELs make use of an epitaxial regrowth design to homogeneously integrate an AlGaAs/GaAs HBT and an InGaAs/GaAs VCSEL. An intracavity contacting scheme involving all three terminals, undoped distributed Bragg reflectors and modulation doping are used to ensure a low-loss laser structure. The first generation of devices showed sub-mA range base threshold current in combination with a high output power close to 2 mW but did not fulfill the requirements for a fully operational transistor laser since the transistor went into saturation before the onset of lasing (IBsat<IBth). From numerical simulations this premature saturation was demonstrated being due to a lateral potential variation within the device and large voltage drops along the base and collector regions. As a remedy to this problem the base region was redesigned for a reduced resistance and transistor current gain, and the saturation current could thereby be extended well beyond threshold. These devices showed excellent transistor-laser characteristics with clear gain-compression at threshold, mA-range base threshold current, mW-range output power, high-temperature operation to at least 60°C, low collector-emitter offset voltage and record-low power dissipation during lasing. Furthermore, the collector-current breakdown characteristics was investigated in some detail and it is concluded that this, in contrast to previous models, presumably not is due to an intracavity photon reabsorption process but rather to a quantum-well band-filling effect.

Ort, förlag, år, upplaga, sidor
Stockholm: KTH Royal Institute of Technology, 2014. s. vii, 64
Serie
TRITA-ICT/MAP AVH, ISSN 1653-7610 ; 2014:16
Nationell ämneskategori
Elektroteknik och elektronik
Forskningsämne
Elektro- och systemteknik
Identifikatorer
urn:nbn:se:kth:diva-156841 (URN)978-91-7595-363-2 (ISBN)
Disputation
2014-12-19, Sal/hall C, Electrum, KTH-ICT, Kista, 10:00 (Engelska)
Opponent
Handledare
Anmärkning

QC 20141203

Tillgänglig från: 2014-12-03 Skapad: 2014-12-02 Senast uppdaterad: 2015-04-13Bibliografiskt granskad

Open Access i DiVA

Fulltext saknas i DiVA

Övriga länkar

Förlagets fulltextScopus

Personposter BETA

Hammar, Mattias

Sök vidare i DiVA

Av författaren/redaktören
Xiang, YuYu, XingangZabel, ThomasHammar, Mattias
Av organisationen
Integrerade komponenter och kretsar
I samma tidskrift
Optics Express
Elektroteknik och elektronik

Sök vidare utanför DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetricpoäng

doi
urn-nbn
Totalt: 262 träffar
RefereraExporteraLänk till posten
Permanent länk

Direktlänk
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annat format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annat språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf