2013年7月18日星期四

What is GaAs?

GaAs(Gallium arsenide) is a compound semiconductor material,a mixture of two elements, gallium (Ga) and arsenic (As). The uses of Gallium arsenide are varied and include being used in LED/LD, field-effect transistors (FETs), and integrated circuits (ICs).
GaAs Basic Parameters at 300K
Crystal structureZinc Blende
Group of symmetryTd2-F43m
Number of atoms in 1 cm34.42·1022
de Broglie electron wavelength240 A
Debye temperature360 K
Density5.32 g cm-3
Dielectric constant (static )12.9
Dielectric constant (high frequency)10.89
Effective electron mass me0.063mo
Effective hole masses mh0.51mo
Effective hole masses mlp0.082mo
Electron affinity4.07 eV
Lattice constant5.65325 A
Optical phonon energy0.035 eV
GaAs Electrical Parameters
Breakdown field≈4·105 V/cm
Mobility electrons≤8500 cm2 V-1s-1
Mobility holes≤400 cm2 V-1s-1
Diffusion coefficient electrons≤200 cm2/s
Diffusion coefficient holes≤10 cm2/s
Electron thermal velocity4.4·105 m/s
Hole thermal velocity1.8·105m/s
And now we introduce types of uses of GaAs based devices:
Types and Uses of GaAs Electronic Devices
Electronic devicesMaterial(layer/substrate)Application Technology TendsMaterial Required
Digital ICGaAs/GaAs Ultra-high-speed computersHigh level of integration 
(MESFETHEMT)GaAlAs/GaAsPC,ATM,Image Processing Low operating voltage 
Microvave DevicesGaAs/GaAsMobile communications, satellite broadcastingHigh power, low noise,Low cost
(MESFETHEMT,GaAlAs/GaAsLow-noise receiver, amplifiedHigh level of integrationLarge diameter
Simulation GaAlAs/InGaAs/GaAsAutomotive anti-collision system Low operating voltageLow Vth 
ICMMICHBT)InGaP/GaAs/GaAsPAR  
Hall devicesGaAs/GaAsAuto VTRHigh sensitivityLow cost,large diameter
FDD sensors
Position detection sensor
Types and Uses of GaAs Optoelectronic Devices
Optoelectronic devicesMaterial(layer/substrate)ApplicationTechnology TendsMaterial Required
Visible Light LEDGaAsP/GaAs( red )                      
GaAlAs/GaAs(high brightness red)  
InGaAlP/GaAs(high brightness 
orange/yellow)
Home appliances, DA, electronic equipment High brightnessLow costs
Car lightsShort wavelengthLarge diameter 
Lights in fax  
IR LEDGaAs/GaAs                                       
GaAlAs/GaAs
Home appliances,DA 
machinery in Electronics industry High power  
Remote control and optocoupler  
Optical circuit breaker  
Semiconductor LaserGaAs/GaAsOptical communication switch  
Short Wavelength LDGaAlAs/GaAs(780nm)        
 InGaAlP/GaAs(680630nm)
 Light-emitting devices for Optical LAN,light emitting devices for testing equipments,CD,MD,Laser printer,CD-Rom,DVD-Rom,DVD-RAMHigh Power,high level of integration,low wavelengthLow density,large diameter,low cost
Solar CellGaAs/GaAsSatellite broadcasting, communications,Unmanned meteorological stations 

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