The AlGaInN quaternary alloy system is uniquely suited for numerous device applications because the bandgap can be varied from 1.9 to 6.2 eV by changing the alloy composition. Growth of epitaxial device-quality group III (Al, Ga, In) nitride films has been hindered by a lack of suitably lattice matched substrates, the large equilibrium dissociation pressure of N2 from the nitrides at typical growth temperatures, and predeposition reactions in the commonly employed metal−organic chemical vapor (MOCVD) precursors. The most successful films have been grown at temperatures in excess of 900 °C by MOCVD. However, high growth temperatures may limit compatibility and incorporation of group III nitrides with existing fabrication technologies and devices. Attempts to lower deposition temperature include activated nitrogen sources and alternative precursors. This review will discuss improvement in film properties as a function of growth chemistry and will focus on MOCVD precursors used specifically for the growth of...

Growth of Group III Nitrides. A Review of Precursors and Techniques

Thin films of aluminum nitride are deposited at 350 K on silicon, GaAs, fused quartz, and KBr substrates using gas-phase 193 nm excimer laser photolysis of trimethylamine alane and ammonia precursors without a thermally induced or a spontaneous reaction between them, resulting in AlN thin films that are amorphous, smooth and featureless having a band gap of 5.8 eV, a refractive index of 2.0, a breakdown electric field breakdown of 10 8 V/m, a low-frequency dielectric constant of 6.0-6.9, high-frequency dielectric constant of 3.9-4.0, well suited for many thin film applications.

Low temperature photolytic deposition of aluminum nitride thin films

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 measure...

J.J. Alwan

Papers

Photochemical growth of GaN and AlN on sapphire (0001) and GaAs(100)