Applied Physics Letters · 2002 · 51 citations · 12 references
EngineeringMaterials EngineeringMaterials ScienceCondensed Matter PhysicsElectronic MaterialsSemiconductor MaterialsDopingSemiconductor HeterostructuresSemiconductor InterfacesSemiconductor PhysicsSemiconductor SurfacesSurface PhysicsConductionConduction BandFermi LevelFermi Level PinningHeterostructuresSurface Band BendingTwo-dimensional Electron GasesTwo-dimensional Semiconductor Heterostructures
Mechanism on the formation of two-dimensional electron gas (2DEG) at the interface of undoped AlxGa1−xN with undoped GaN was interpreted through surface band bending observed using synchrotron radiation photoemission spectroscopy. The surface Fermi level was independent of AlxGa1−xN thickness and Al content in AlxGa1−xN, showing Fermi pinning to surface states at 1.6 eV below conduction band minimum. Oxygen donor impurities in undoped AlxGa1−xN, unintentionally doped during the growth, led to the formation of large density of 2DEG (>∼1013/cm3) at the AlxGa1−xN/GaN interface via electron generation.
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