Properties of AlN films grown at 350 K by gas-phase excimer laser photolysis

Abstract

Thin films of aluminum nitride have been deposited at 350 K on Si(100), fused quartz, and KBr substrates using gas-phase excimer laser photolysis of trimethylamine alane and ammonia at 193 nm. Depth profiles of these laser-grown films using secondary-ion-mass spectrometry indicate that no AlN film is produced without photolytic processes. The films are amorphous, and are smooth and featureless as established by scanning electron microscopy and atomic force microscopy. Optical-absorption spectra of these films have been measured and a band gap of 5.8 eV has been calculated from these spectra. Ellipsometric measurements have been used to determine a refractive index of 1.9–2.0 for these films. The infrared spectrum of the films displays a characteristic absorption due to TO phonons in AlN. Electrical measurements reveal that the films have excellent dielectric properties. A breakdown electric field of 108 V m−1 and a low-frequency dielectric constant of 6.0–6.9 have been established from I–V and C–V measurements, respectively.