Ion-beam-produced damage and its stability in AlN films

Abstract

Structural characteristics of single-crystal wurtzite AlN epilayers (grown on sapphire substrates) bombarded with 300 keV Au+197 ions at room and liquid-nitrogen temperatures (RT and LN2) are studied by a combination of Rutherford backscattering/channeling spectrometry and cross-sectional transmission electron microscopy. Results reveal extremely strong dynamic annealing of ion-beam-generated defects in AlN. Lattice amorphization is not observed even for very large doses of keV heavy ions at LN2. An increase in irradiation temperature from LN2 to RT has a relatively small effect on the production of stable structural damage in AlN. In contrast to the case of AlxGa1−xN with x⩽0.6, neither damage saturation in the crystal bulk (below the random level) nor preferential surface disordering is revealed for AlN. Results also show that structural lattice disorder produced in AlN by high-dose keV heavy-ion bombardment is stable to rapid thermal annealing at temperatures as high as 1000 °C.