Growth of GaN/AlN and AlGaN by MOCVD using triethylgallium and tritertiarybutylaluminium

Films of aluminium nitride (AlN) with thicknesses in the range from 200 to 3600 Angstrom have been deposited at 1050 degrees C by low-pressure MOCVD. Using an alternative precursor, tritertiarybutylaluminium ((t)Bu(3)Al), and ammonia (NH3), we have grown AlN 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 150 arcsec. Therefore, we used the thin AlN films as buffer layers for the deposition of gallium nitride (GaN) at 950 degrees C using triethylgallium (Et(3)Ga). Aluminium gallium nitride (AlxGa1-xN) with aluminium contents x from 0 to 0.5 were grown using a mixture of Et(3)Ga and (1)Bu(3)Al. The structural and optical properties of GaN, AlGaN and AlN were verified by X-ray diffraction (XRD), spectrally resolved photoconductivity (SPC), photothermal deflection (PDS) and photoluminescence spectroscopies.