Basicinformation
Chemicalformula:GaAs
Molecularweight:144.645
CASNumber:1303-00-0
EINECSNo.:215-114-8
Physicalandchemicalproperties
Density:5.31g/cm3
Meltingpoint:1238℃
Refractiveindex:3.57
Relativedielectricconstant:13.18
Electronaffinity:4.07eV
Latticeenergy:5.65×10-10m
Forbiddenbandwidth:1.424e(300K)
Electronmobility:8500cm2/(V·s)(300K)
Appearance:blackgraysolid
Safetyinformation
Safetyterm
S20/21:Whenusingdonoteat,drinkorsmoke.
Whenusing,donoteat,drinkorsmoke.
S28:Aftercontactwithskin,washimmediatelywithplentyof...(tobespecifiedbythemanufacturer).
Aftercontactwithskin,washimmediatelywithplentyof...(tobespecifiedbythemanufacturer).Specifiedbythemanufacturer)Flush.
S45:Incaseofaccidentorifyoufeelunwell,seekmedicaladviceimmediately(showthelablewherepossible).
Incaseofaccidentorifyoufeelunwell,seekmedicaladviceimmediately(showthelablewherepossible).
Showthelabelwhenpossible).
S60:Thismaterialand/oritscontainermustbedisposedofashazardouswaste.
Thismaterialand/oritscontainermustbedisposedofashazardouswaste.
S61:Ifswallowed,donotinducevomiting:seekmedicaladviceimmediatelyandshowthiscontainerorlabel.
Donotinducevomitingafterswallowing:Seekmedicalattentionimmediatelyandshowthecontainerorlabel.
RiskTerminology
R23/25:Toxicbyinhalationandifswallowed.
Inhalationandswallowingaretoxic.
Materialproperties
GaAshassomebetterelectronicpropertiesthanSi,whichenablesGaAstobeusedinapplicationshigherthan250GHz.IfequivalentGaAsandSicomponentsareoperatedathighfrequenciesatthesametime,GaAswillproducelessnoise.AlsobecauseGaAshasahigherbreakdownvoltage,GaAsismoresuitableforoperationinhigh-powerapplicationsthanthesameSidevices.Becauseofthesecharacteristics,GaAscircuitscanbeusedinmobilephones,satellitecommunications,microwavepoint-to-pointconnections,radarsystems,andotherplaces.GaAswasusedtomakeGanndiodes,microwavediodes,andGunndiodestoemitmicrowaves.
AnotheradvantageofGaAs:Itisamaterialwithadirectenergygap,soitcanbeusedtoemitlight.Siisanindirectenergygapmaterialandcanonlyemitveryweaklight.(However,recenttechnologycanalreadyuseSitomakeLEDsandusetheminlasers.)
Technologyprocess
Asasecond-generationsemiconductor,galliumarsenidesinglecrystalisexpensivebecauseofitshighprice.Knownasthe"semiconductoraristocracy".OnJuly31,2001,Chinesescientistsannouncedthattheyhadmasteredanewtechnologyforproducingthismaterial,makingChinaanothercountrythathasmasteredthistechnologyafterJapanandGermany.BeijingGeneralResearchInstituteofNonferrousMetalsannouncedthatthefirst4-inchdiameterVCZsemi-insulatinggalliumarsenidesinglecrystalwassuccessfullydrawninChina.
Accordingtoexperts,galliumarsenidecansimultaneouslyprocessoptoelectronicdataonachip,soitiswidelyusedinmanyoptoelectronicfieldssuchasremotecontrol,mobilephones,DVDcomputerperipherals,andlighting.Inaddition,becauseitselectronmobilityis6timeshigherthanthatofsilicon,galliumarsenidehasbecomeanecessityforultra-high-speed,ultra-high-frequencydevicesandintegratedcircuits.Itisalsowidelyusedinthemilitaryfield.Itisanimportantmaterialforlaser-guidedmissiles.ItonceshowedgreatpowerintheGulfWarandwonthereputationof"GaAsdefeatssteel."ItisreportedthatthepriceofaGaAssinglechipisapproximately20to30timesthatofasiliconsinglechipofthesamesize.Despitethehighprice,theannualsalesofgalliumarsenidesemiconductorsintheworldarestillmorethan1billionUSdollars.IntheTenthFive-YearPlan,mycountrywillrealizetheindustrializationofthisproducttooccupytheinternationalmarket.
Mainstreamindustrializedgalliumarsenidegrowthprocessesinclude:Czochralskimethod(Czmethod),horizontalBridgmanmethod(HB),verticalBridgmanmethod(VBmethod)andverticalgradientsolidificationmethod(VGFmethod)andsoon.Theabovemethodshavetheirownadvantagesanddisadvantages.Inadditiontotheactualprocesspreparationmethod,theotheristorealizethenumericalsimulationofthegalliumarsenidecrystalgrowththroughthecomputer.SimulationoftheCZmethodgrowthprocess;thedomesticBeijingGeneralResearchInstituteofNonferrousMetalshasmadeeffectivecalculationsandsimulationsforthemicro-defectsinthecrystalgrowthprocessandtheinfluenceofthemeltandairflowonthecrystalgrowthprocess,whichprovidestechnicalguidanceforthepreparationofcrystalgrowthTheroleof.
Toxicologicalinformation
ThetoxicityofGaAshasnotbeenthoroughlystudied.BecauseitcontainsAs,researchhaspointedoutthatAsishighlytoxic.However,becauseGaAscrystalsareverystable,ifthebodyabsorbsasmallamountofGaAs,itcanactuallybeignored.Whenthewaferpolishingprocess(grindingGaAswaferstomakethesurfaceparticlessmaller),thesurfaceareawillreactwithwatertoreleaseordecomposealittleAs.