Laser deposition of AlN thin films on InP and GaAs

Abstract

Aluminium nitride thin films (~1000 Å) were deposited by pulsed laser (ruby, 30 ns) evaporation on compound semiconductors GaAs and InP for fabrication of metal-insulator-semiconductor (MIS) diodes. The deposition was carried out with a laser energy density of 2.5 J.cm^-2 at a rate of 10^-11 Å/pulse at ~10^-6 Torr, the substrate temperature being 300 K. Low-angle X-ray diffraction showed the films to have a wurtzite structure. The resistivity of the films was 5× 10¹² Ω-cm with a breakdown field of 1-2× 10⁶ V-cm. The dielectric constant of the films was in the range of 7.5-7.8. A lower value of interface state density was obtained on InP (~1.8× 10¹¹ cm^-2.eV^-1) rather than on GaAs (~8× 10¹¹ cm^-2.eV^-1). These results are compared with earlier studies of laser-deposited BN films on InP.