화학공학소재연구정보센터
Journal of Vacuum Science & Technology B, Vol.24, No.3, 1572-1576, 2006
Atomic force microscopy study of sapphire surfaces annealed with a H2O flux from a baffled molecular-beam epitaxy effusion cell loaded with Al(OH)(3)
We present an atomic force microscopy (AFM) study of sapphire surfaces that contain scratches with various severities. The objective was to observe the effects of substrate annealing at 850 degrees C for 200 min with a H2O-based overpressure resulting from an Al(OH)(3) powder that was thermally cracked at 1200 degrees C. The Al(OH)3 was decomposed into Al2O3 and H2O according to a partial Bayer process in a modified molecular-beam epitaxy (MBE) effusion cell, which was equipped with homemade baffles placed at its outlet. These homemade, simple-to-construct tantalum baffles allow for the selective outfluxing of gaseous species, from those that are solid based. A UTI (TM) 100C-model mass spectrometer was used to monitor the species present at the sapphire surface during annealing. Any aluminum-based solid species from the Al(OH)3 were not observed in the mass spectrum, although the H2O-based species were. The sapphire substrates were annealed in a Varian Gen II (TM) MBE system, with H2O beam equivalent pressures (BEPs) of 5 x 10(-6) and 2 x 10(-5) Torr, as well as with no H2O flux at all. The AFM images show that the samples annealed with a higher H2O BEP of 2 x 10(-5) Torr had noticeably less severe surface scratches than the samples that were annealed with lower H2O BEPs. (c) 2006 American Vacuum Society.