ABSTRACT
SemiconductorlasersbasedonGaAsandrelatedmaterialsarethesubject ofavastpartoftheresearchinthisfield.Thefirstsuggestiontouse semiconductorsaslasermaterialswasexpressedbyAigrainasearlyas1958. ElectroluminescencespectrumnarrowinginGaAsat77KobservedbyNasledov etalin1962asexperimentalevidenceofhigh-efficiencyradiativerecombination gaveastrongimpulsetothelaser-orientedactivity.Thefirsthomojunction semiconductorlaserswerecreatedusingGaAsin1962almostsimultaneously bythreegroupsofAmericanscientists(Halletal1962,Nathanetal1962 andQuistetal1962).Inthesameperiod,HolonyakandBevacqua(1962) reportedlasinginGaAsP.Thoseearlydeviceswereonlyabletooperateatlow temperaturesduetotheveryhighthresholdcurrentdensity.Thesolutiontothis problemwasproposedin1963byAlferovandKazarinov(1963)andsoonafter thatbyKroemer(1963).Theideawastousedoubleheterostructurestoensure electricalandopticalconfinementandreducethethresholdcurrent.Atthattime thepossibilityofefficientcarrierinjectionthroughaheterojunctionstillseemed tobeveryvaguebecauseoftheextremelyhighcarrierrecombinationrateon theinterfaceofpolycrystallineheterojunctions.However,by1969Kresse!and Nelson(1969),Panishetal(1969)andHayashietal(1969)successfullyapplied liquidphaseepitaxytoobtainlaser-qualityheterojunctionsinGaAs-AIGaAs withadecreasedthresholdcurrentdensity.Abreakthroughwasmadein1970 whenAlferov'sgroupachievedcontinuouswaveoperationofaGaAs-AIGaAs double-heterostructurelaseratroomtemperature(Alferovetal1971),againin GaAs-basedmaterial.Abreathtakingcompetitiontookplaceatthattimeas witnessedbyCaseyandPanish(1978),impressivebyitsscientificsignificance aswellasbyemotionalstrength.
