REFLECTANCE-DIFFERENCE PROBING OF SURFACE KINETICS OF (001) GAAS DURING VACUUM CHEMICAL EPITAXY

A reflectance-difference (RD) study of the kinetics of various surface processes involved in the growth of GaAs from triethylgallium and arsine is presented. During triethylgallium exposure of an As-stabilized (001) GaAs surface, an initial linear RD response is observed, similar to what has previously been reported for trimethylgallium. We show that in the case of triethylgallium an over-saturation of the surface occurs, which results in complex transients in the RD response and, for a critical dose, in a loss of the surface coherency as determined by the disappearance of RD growth oscillations. It is found that the arsine reactivity on the over-saturated surface is much higher that that on the Ga-stabilized surface. The arsine-induced RD transient is compared with the kinetics of the re-establishment of a perfect As-stabilized surface, using the amplitude of RD-detected growth oscillations as a probe of the status of the surface.