Laser Deposition of AlN Thin Films on InP and GaAs

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 5×10 12 Ω-cm with a breakdown field of 1-2×10 6 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 (∼1.8×10 11 cm -2 ·eV -1 ) rather than on GaAs (∼8×10 11 cm -2 ·eV -1 ). These results are compared with earlier studies of laser-deposited BN films on InP.