ABSTRACT
Since the innovative technique of growing high quality GaN on sapphire substrateusingalowtemperatureAlNbufferlayerwasdiscoveredby Akasakiandcoworkers(Amanoetal.,1986),thegrowthofIII-nitrideshas beendevelopedondifferentsubstratesusingvariousbufferlayers(Liuand
CONTENTS
3.1 Introduction ..................................................................................................99 3.2 Approaches for Initial Growth ................................................................. 101
3.2.1GaN Buffer Layer ........................................................................... 102 3.2.2Metal Al Predeposition ................................................................. 103 3.2.3 AlN and AlGaN Buffer Layers .................................................... 105 3.2.4 Other Buffers .................................................................................. 105 3.2.5 Intermediate Layer ......................................................................... 107
3.3Epitaxial Lateral Overgrowth of Semipolar and Nonpolar GaN Grown on Si ................................................................................................ 107 3.3.1 Selective Area Growth .................................................................. 108 3.3.2 Formation of Pyramidal GaN on Si............................................. 108 3.3.3 Behavior of the Threading Dislocation in GaN Grown on Si ... 109 3.3.4Selective Growth of GaN on Si (001) ........................................... 110 3.3.5ELO of (1-101) GaN ......................................................................... 111 3.3.6 ELO of (11-22) GaN on (113) Si ...................................................... 113 3.3.7 ELO of (11-20) GaN on (110) Si ...................................................... 113 3.3.8 ELO of m-Plane (1-100) GaN on (112) Si ....................................... 114
3.4Photonic Devices ........................................................................................ 115 3.4.1LEDs on 2 in. Si Substrates ........................................................... 115 3.4.2 LEDs on Large Size Si Substrates (>5 in. in Diameter) ............. 117 3.4.3 LEDs on Semipolar GaN/Si Templates ....................................... 124
3.5 Summary and Future Perspectives ......................................................... 127 Acknowledgments .............................................................................................. 127 References ............................................................................................................. 128
Edgar,2002).Nowadays,mostIII-nitridedevicesaremadeonGaN/sapphire templatesoronsiliconcarbide(SiC).However,thefabricationofphotonic devicesonSisubstrateshaslongbeendesiredforthepurposeofintegrating photonicdeviceswithSi-basedelectronicdevices.Butbecauseofthelarge latticemismatchbetweenSiandIII-Vsemiconductors,directgrowthand fabricationofphotonicmaterialsanddevicesonSisubstrateshavebeena challenge.Twenty-ˆveyearsago,thegrowthofGaAsonSisubstratewas demonstratedtorealizetheintegrationofcompoundsemiconductordevices onSisubstrates(Sogaetal.,1985).However,thequalityoftheheteroepitaxiallayerwasinferiortothatobtainedonGaAsorInPsubstrates.One oftheissueshasbeenthedifferenceinthermalexpansioncoefˆcients,which inducesthewafertobend,preventingˆnelithographyprocesses.Withthe recentrapidprogressmadeinbothnitridematerialsanddevices(though mostlyonsapphireandSiCsubstrates),nitridematerialsanddevicesonSi substratesnaturallyattractedmuchattentionandworldwideeffortfromthe nitride community.
