Surface chemical treatment for the cleaning of AlN and GaN surfaces

In this study, various surface cleaning techniques for the removal of carbo n (C) and oxygen (O) from AIN and GaN were investigated. Auger electron spe ctroscopy (AES) and secondary mass ion spectroscopy were used to monitor th e presence of surface C and O, and atomic force microscopy was used to moni tor surface roughness. AES analysis showed that ex situ ultraviolet/ozone ( UV/O-3) and wet chemical treatments based on HF and HCl were very effective in removing surface C and reducing the native oxide on both AIN and GaN, A fter H-2 and N-2 plasma treatments in ultrahigh vacuum at temperatures of 7 50 and 900 degrees C, clean GaN surfaces could br achieved with in the dete ction limits of AES. An oxygen-free AW surface could not be obtained within the detection limits of AES. SIMS analysis showed that concentrations of s urface C and O up to 3 x 10(20) and 2 x 10(22) cm(-3), respectively, still exists on plasma-treated GaN. The results of this study indicate that ex si tu UV/O-3 followed by H-2/N-2 plasma treatment is highly effective in reduc ing the C and O contamination at the GaN surface, bur that further in situ methods are needed to obtain clean GaN and AlN surfaces. None of the variou s cleaning methods were found to affect the surface roughness. (C) 2000 The Electrochemical Society. All rights reserved.