Control of stress and threading dislocation density in the thick GaN/AlN buffer layers grown on Si (111) substrates by low- temperature MBE

摘要

Wereportonsuccessfulgrowthbyplasma-assistedmolecularbeamepitaxyonaSi(111)substratecrack-freeGaN/AlNbufferlayerswithathicknessmorethan1μm.Thelayersfabricatedatrelativelylowgrowthtemperatureof780°Chaveatroomtemperaturetheresidualcompressivestressof-97MPa.IntrinsicstressevolutionduringtheGaNgrowthwasmonitoredinsituwithamulti-beamopticalsystem.Strongdependenceofastressrelaxationratiointhegrowinglayervsgrowthtemperaturewasobserved.Thebest-qualitycrack-freelayerswithTDsdensityof~?109cm-2androughlyzerobowingwereobtainedinthesamplewithsharp2D-GaN/2D-AlNinterface...