Physical and electrical properties of reactive molecular-beam-deposited aluminum nitride in metal-oxide-silicon structures

We report on the physical and electrical properties of AlN as grown by reactive-atomic-beam deposition under various growth and anneal conditions. The physical characterization shows that AlN grown on hydrogen terminated (HF-last) Si has a thin layer of Si3N4 at the interface while growth of AlN on SiO2 or Al2O3 suffers from nucleation problems. The AlN on HF-last Si, grown and annealed at 650 degreesC, shows high interfacial quality and four to five orders of magnitude lower leakage current as compared to SiO2. In contrast, poor interfacial properties and leakage current are reported for the AlN grown on SiO2 or Al2O3. The relative permittivity of the AlN is found to be close to 18 and the equivalent thickness of the interfacial layer is approximately 6 Angstrom. The effective electron mobility in Al-gated N-channel metal-oxide-silicon field-effect transistors with a 22 Angstrom thick AlN layer peaks at similar to130 cm(2)/V s. The relatively low mobility is attributed to a combination of high concentration of fixed charge (>5x10(12) cm(-2)) and charge trapping. (C) 2003 American Institute of Physics.