GROWTH OF GAN ALN BY LOW-PRESSURE MOCVD USING TRIETHYLGALLIUM AND TRITERTBUTYLALUMINIUM/

Films of aluminum nitride (AIN) with thicknesses in the range from 200 to 3600 Angstrom have been deposited at 1050 degrees C by low-pressur e MOCVD. Using an alternative precursor, triterbutylaluminium (Bu(3)(t )Al), and ammonia (NH3), we have grown AIN on sapphire (c-Al2O3). At a growth rate of 0.35 mu m/h, the FWHM of the rocking curve measured by X-ray diffraction was below 320 arcsec. Therefore, we used the thin A IN films as buffer layers for the deposition of gallium nitride (GaN) at 950 degrees C using triethylgallium (Et(3)Ga). The improved structu ral and optical properties of GaN were verified by XRD and Raman, phot othermal deflection and photoluminescence spectroscopies. The influenc e of the buffer layer thickness on the optical properties such as the sub-bandgap absorption, the Raman-active phonons and photoluminescence are presented.