Chemical Vapor Deposition of Gallium Nitride from Diethylgallium Azide

Pyrolysis of diethylgallium azide in a conventional hot-wall chemical vapor deposition reactor at 350 degrees C followed by in situ annealing at 600 degrees C results in gallium nitride films. Film purity has been determined by electron microprobe, Auger electron spectroscopy, and Rutherford backscattering spectroscopy. The films are stoichiometric GaN, with carbon and oxygen content below 2%. Film structure has been examined by X-ray diffraction and by scanning and transmission electron microscopy. The films are polycrystalline and show diffraction patterns characteristic of the expected hexagonal wurtzite structure. Mass spectroscopic analysis of the product gases suggests the films are formed by successive 3-hydride eliminations of ethylene from the ethyl groups and loss of nitrogen from the azide. The effect of annealing, as studied by infrared spectroscopy, is the loss of hydrogen from the film with a concomitant increase in gallium-nitrogen bonding.