High-quality InN layers grown on sapphire substrates by plasma-assisted molecular-beam epitaxy were characterized by using mono-energetic positron beams. The carrier concentrations of the films were controlled by Si doping (2.1 x 1018 to 1.4 x 1019/cm3), and the highest obtained Hall mobility was 1300cm2/Vs. The Doppler broadening spectra of the annihilation radiation and the lifetime spectra of positrons were measured as a function of the incident positron energy for undoped and Si-doped InN films. The line-shape parameter S increased with increasing carrier concentration, suggesting the introduction of vacancy-type defects by a Fermi-level effect. The major defect species were varied with carrier concentration, and its species were identified as In vacancies (VIn) or their related defects.

Vacancy-Type Defects in Si-Doped InN Grown by Plasma-Assisted Molecular-Beam Epitaxy Probed using Mono-Energetic Positron Beams. A.Uedono, S.F.Chichibu, M.Higashiwaki, T.Matsui, T.Ohdaira, R.Suzuki: Journal of Applied Physics, 2005, 97[4], 043514 (5pp)