Rapid Note HREELS investigation of hydrogenated and deuterated GaN{0001} surfaces

The vibrational properties of clean, Hand D-covered GaN{0001} surfaces were investigated by high-resolution electron energy-loss spectroscopy. Auger electron spectroscopy and low-energy electron diffraction were utilized to monitor the surface cleanliness and structure, respectively. At the clean surface the Fuchs-Kliewer surface phonon frequency was determined to 700 cm−1 (86.8 meV). For the adsorbatecovered surfaces current structure models predict only Ga-H vibrations for surfaces of either polarity. Despite of this, the HREEL-spectra of the hydrogenated sample show a new loss structure at 3255 cm−1 (403.6 meV) and a shoulder at 1900 cm−1 (235.6 meV) which are attributed to N-H and Ga-H stretching vibrations, respectively. After deuterium exposure an isotope shift occurs. Again, a N-adsorbate vibration is clearly resolved. A Ga-D bending mode is observed at 390 cm−1 (48.4 meV), indicating that vibrations of both species are present. PACS. 82.65.My Chemisorption – 68.35.Ja Surface and interface dynamics and vibrations – 79.20.-m Impact phenomena (including electron spectra and sputtering)