Optical Semiconductor DevicesOptical Semiconductor Devices

The Foundations of the Laser Diode

The Development of the Modern The Development of the Modern Laser DiodeLaser Diode

Founding principlesFounding principles

ElectroluminesenceElectroluminesence

Band TheoryBand Theory

Discovery of the LEDDiscovery of the LED

The Challenge of the Laser DiodeThe Challenge of the Laser Diode

Laser Diodes TodayLaser Diodes Today

Overlooked BeginningsOverlooked Beginnings

Henry J Round (1907)Henry J Round (1907)

Oleg Oleg LosevLosev

(1923)(1923)

ElectroluminescenceElectroluminescence

Electroluminescence in silicon carbide crystal fibersElectroluminescence in silicon carbide crystal fibers

The Glowing DiodeThe Glowing Diode

Luminous Luminous carborundum [silicon carborundum [silicon carbide] detector and carbide] detector and detection with detection with crystalscrystals

(1927)(1927)

Light RelayLight Relay

Band Theory of SolidsBand Theory of Solids

Bonding Structure of Crystal AtomsBonding Structure of Crystal Atoms

Band Theory of SolidsBand Theory of Solids

Doping of the latticeDoping of the lattice

Band Theory of SolidsBand Theory of Solids

Schottky DiodeSchottky Diode

Band Diagram of a Schottky DiodeBand Diagram of a Schottky Diode

vc EEhc

=

LED ConstructionLED Construction

Edge Emitting LEDEdge Emitting LED

Surface Emitting LEDSurface Emitting LED

Why LEDWhy LEDs?s?

High Internal Quantum High Internal Quantum Efficiency RatingsEfficiency Ratings

High overall efficiency ratingHigh overall efficiency rating

LED SpectrumLED Spectrum

Many Frequencies PossibleMany Frequencies Possible

Laser Diode ChallengesLaser Diode Challenges

Wavelength SpectrumWavelength Spectrum

Random Light EmissionRandom Light Emission

Phase Phase CoheranceCoherance

HeatHeat

The Challenge of LasingThe Challenge of Lasing

ProblemsProblems

Large Injection CurrentLarge Injection Current

Additional HeatAdditional Heat

SolutionsSolutions

Pulse OperationPulse Operation

Active CoolingActive Cooling

CollimationCollimation

Cleaved Mirror Resonator CavityCleaved Mirror Resonator Cavity

Laser Diode

0.2

So What About the Heat?So What About the Heat?

The SolutionThe Solution

Advances in Materials ProductionAdvances in Materials Production

HeterostructuresHeterostructures

HeterojunctionHeterojunction

Double HeterojunctionDouble Heterojunction

Double Heterojunction VisualizationDouble Heterojunction Visualization

Thank You

References(1) http://hyperphysics.phy-astr.gsu.edu/Hbase/solids/

(2) S. M. Sze, Physics of Semiconductor Devices, 2nd ed., John Wiley & Sons, New York, 1981(3) E. Fred Schubert, Light-Emitting Diodes, 2nd ed., Cambridge University Press, New York, 2006

(4) Mitsuo Fukuda, Optical Semiconductor Devices, John Wiley & Sons, New York, 1999(5) B Van Zeghbroeck, http://ece-www.colorado.edu/~bart/book/movie/movie1.htm, 2004

http://ece-www.colorado.edu/~bart/book/movie/movie1.htm

Optical Semiconductor DevicesThe Development of the Modern Laser DiodeOverlooked BeginningsElectroluminescenceThe Glowing DiodeBand Theory of SolidsBand Theory of SolidsBand Theory of SolidsSchottky DiodeLED ConstructionWhy LEDs?LED SpectrumLaser Diode ChallengesThe Challenge of LasingCollimationSo What About the Heat?The SolutionHeterojunctionDouble HeterojunctionDouble Heterojunction VisualizationThank You