Mechanism of two-dimensional electron gas formation in AlxGa1-xN/GaN 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 (>similar to10(13)/cm(3)) at the AlxGa1-xN/GaN interface via electron generation. (C) 2002 American Institute of Physics.