Investigation of blistering kinetics in hydrogen implanted aluminium nitride

Epitaxial layers of aluminium nitride (AlN) grown on sapphire by hydride vapour phase epitaxy (HVPE) were implanted with 100 keV hydrogen, H+2, ions with doses in the range of 5 × 1016–2.5 × 1017 cm−2 and subsequently annealed in ambient air at temperatures between 450 and 750 ◦C in order to determine the kinetics of surface blister formation in AlN. The Arrhenius plot of the blistering time versus temperature shows two different activation energies for the formation of surface blisters: 0.44 eV in the higher temperature regime of 550–750 ◦C and 1.16 eV in the lower temperature regime of 450–550 ◦C. The implantation-induced damage was analyzed by cross-sectional transmission electron microscopy, which revealed a band of defects extending from 330 to 550 nm from the surface of AlN. The XTEM image of the implanted and annealed AlN displayed clearly the formation of microcracks that ultimately lead to the formation of surface blisters. (Some figures in this article are in colour only in the electronic version)