INVESTIGATION OF THE INITIAL CHEMISORPTION AND REACTION OF FLUORINE (XEF2) WITH THE GAN(0001)-(1X1) SURFACE

X-ray and ultraviolet photoemission and X-ray-excited Auger spectrosco pies have been used to study the initial chemisorption and reaction of fluorine (XeF2) with GaN(0001)-(1 X 1) surfaces. An inhomogeneous lay er is formed, with a saturation coverage of Theta(F)(sat) approximate to 0.67 monolayers, which is stable up to similar to 550 degrees C. Hi gher coverages are attained under similar conditions on surfaces damag ed by N-ion bombardment. Band bending on the ordered surface is essent ially eliminated by chemisorbed F. Ga atoms bonded to two or three F a toms are identified in the fluorinated layer through the appearance of a chemically-shifted satellite in the Ga 3d XPS and of other features associated with GaF3. However, the additional presence of a 'GaF-like ' monofluoride and/or N-F bonds cannot be excluded. (C) 1997 Elsevier Science B.V.