Interfacial properties of AlN and oxidized AlN on Si

We report on the characteristics of metal-insulator-semiconductor (MIS) capacitors with aluminum nitride (AlN) as the insulator material. AlN has been grown on (1 1 1) Si by means of molecular beam epitaxy (MBE) and DC magnetron sputtering (SPU). AlN layers have been characterized before and after dry thermal oxidation in O2. By analyzing changes in morphology and electrical properties, different oxidation mechanisms were identified, due to the crystalline quality difference of the AlN samples. In both cases, oxidation at 1000 °C was beneficial for the electrical characteristics of the MIS structures, presumably due to passivation of atom vacancies. Although AlN was only partially oxidized, the flat-band voltage was reduced and the density of interface traps improved. Dominant conduction mechanism was Poole-Frenkel for the SPU sample, and changed to hopping after oxidation.