Localized vibrational modes of carbon-hydrogen complexes in GaN

Localized vibrational modes of carbon-hydrogen complexes in metalorganic ch emical vapor deposition grown GaN on sapphire were studied using a Fourier- transform infrared spectroscopy technique. Three distinctive localized vibr ational modes were observed around 2850, 2922, and 2959 cm(-1) for undoped, Si-, and Mg-doped samples. These peaks are related to CH, CH2, and CH3 def ect complexes, respectively. However, the localized vibrational modes were not observed in some undoped samples, which is indicative of high quality g rown epitaxial layers. It is also observed that the frequencies and intensi ties of the localized vibrational modes are sample dependent. (C) 1999 Amer ican Institute of Physics. [S0003-6951(99)00831-1].