Growth of GaN layer from the single-source precursor (Et2GaNH2)3

In recent years, there has been a great interest in new routes for depositing GaN films in the application of III-V semiconductors. We report herein on the deposition of highly crystalline GaN films by low-pressure MOCVD (in the low-temperature range of 500-700 degrees C and the pressure range of 77-177 mbar) using the single-source precursor (Et2GaNH2)(3). This process was investigated for a variety of substrates (Si(100) and polycrystalline Al2O3) using a cold wall chemical vapor deposition reactor. The thickness of films grown under these conditions ranged from 6 to 8 mu m, and the growth rates varied from 7 to 8 mu m/h. Films deposited at lower temperatures (500-550 degrees C) had a pale yellowish color and were amorphous. At 600 degrees C slightly gray colored films were obtained, while above 650 degrees C high-quality crystalline films were formed, which show diffraction patterns characteristic of the hexagonal wurtzite structure. The films are consistent with the 1:1 stoichiometry of GaN and have carbon and oxygen as impurities; however, cracks were not evident on the surface by SEM examination up to a magnification of 30000. In contrast, samples of GaN deposited under high-vacuum conditions (up to 10(-2) mbar) have neither a 1:1 stoichiometry nor a smooth surface morphology. Atomic force microscopy, scanning electron microscopy, Auger electron microscopy, and energy-dispersive X-ray analyses were used for the study of the structure, composition, and morphology of the films.