MOLECULAR-BEAM STUDIES ON THE LASER-ENHANCED SURFACE-REACTION OF GAAS(100) WITH CHLORINE

A cw supersonic Cl-2 molecular beam coupled with an angle-resolved tim e-of-flight (TOF) technique has been used to investigate the laser-enh anced surface reaction of GaAs(100) with chlorine. The mass and veloci ty distributions of the major reaction products under 1064 nm laser ir radiation have been measured as a function of laser fluence, detection angle, surface temperature and normal component of the translational energy of the incident chlorine molecules. It has been found that incr easing both laser fluence and the translational energy of incident chl orine molecules markedly enhance this surface reaction. The measured f lux angular distributions of major reaction products can be fit satisf actorily with a bi-cosine function. Measurements of the mass and angul ar distributions of reaction products by a modulated molecular beam ma ss spectrometry show that the surface temperature effect is obvious fo r the Cl-2/GaAs(100) ''dark'' thermal reaction. A direct activated dis sociative chemisorption is proposed for the mechanism of Cl-2 chemisor ption on the GaAs(100) surface.