REACTIVE SCATTERING OF CL2 ON GAAS (100) - CL2 AND GACL PRODUCT DISTRIBUTIONS

Time-of-flight and angular distributions of GaCl produced from etching of GaAs (100) by molecular chlorine have been investigated in the ran ge 400-550-degrees-C by pulsed, supersonic, molecular beam scattering. The angular distribution is well described by a cosine curve as expec ted for simple desorption. The TOF distributions of GaCl reveal that i t is produced by two surface processes. The Cl2 distributions also sho w two components: (i) prompt production (accommodation and desorption of incident Cl2) and (ii) delayed chemical production. In all cases th e delayed component is well described by a simple e-t/tau expression. Chemical production Of Cl2 seems strongly linked to the slower GaCl pr oduction and both pathways display the same temperature dependence. Th e time constants obey tau = tau0 exp(E/kT) with E= 110 +/- 10 kJ mol-1 for both pathways.