PROPERTIES OF ALN FILMS GROWN AT 350 K BY GAS-PHASE EXCIMER-LASER PHOTOLYSIS

Thin films of aluminum nitride have been deposited at 350 K on Si(100) , fused quartz, and KBr substrates using gas-phase excimer laser photo lysis of trimethylamine alane and ammonia at 193 nm. Depth profiles of these laser-grown films using secondary-ion-mass spectrometry indicat e that no ALN film is produced without photolytic processes. The films are amorphous, and are smooth and featureless as established by scann ing electron microscopy and atomic force microscopy. Optical-absorptio n spectra of these films have been measured and a band gap of 5.8 eV h as 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 absorpti on due to TO phonons in AIN. Electrical measurements reveal that the f ilms have excellent dielectric properties. A breakdown electric held o f 10(8) V m(-1) and a low-frequency dielectric constant of 6.0-6.9 hav e been established from I-V and C-V measurements, respectively. (C) 19 95 American Institute of Physics.