SURFACE SEGREGATION AND STRUCTURE OF SB-DOPED SI(100) FILMS GROWN AT LOW-TEMPERATURE BY MOLECULAR-BEAM EPITAXY

Sb surface segregation and doping during Si(100) molecular beam epitax y were studied for growth temperatures of 320-500 degrees C. Surface s egregation was analyzed by depth profiling with secondary ion mass spe ctrometry and the results indicate the existence of several distinct d opant concentration- and temperature-dependent surface segregation reg imes: (1) For dilute Sb surface concentrations the measurements reveal a region where bulk and surface concentrations are linearly related, and the surface segregation is described by a constant. However, the e xperimentally determined temperature dependence of the segregation doe s not follow simple kinetics theory, and appreciable surface segregati on is observed at temperatures less than or equal to 400 degrees C. (2 ) At temperatures >350 degrees C, the surface segregation reaches a ma ximum for Sb surface concentrations of 0.5 monolayers. (3) For surface concentrations near 1 monolayer, the surface segregation decreases wi th increasing surface Sb coverage due to dopant interaction within sur face and subsurface layers. In cases where films were grown under very high dopant fluxes, we have identified cone-like defects and stacking faults that are the result of the apparent surface concentration exce eding 1 monolayer.