LEED structures on Si(111) surfaces quenched from elevated-temperature cleavages

Abstract

Silicon wafers were cleaved at various temperatures from room temperature to 720°C and observed by low-energy electron diffraction (LEED). The cooling rate after cleavage was rapid, most of the temperature drop occurring within one or two seconds, in order to freeze-in the surface structures. The (111)2×1 reconstruction alone was observed on surfaces cleaved at temperatures up to 417°C. At higher cleavage temperatures, very slight 5×5 and mostly 7×7 reconstructions co-existed with 2×1, which latter became unobservable after cleavage at 500°C. At cleavage temperatures above 550°C, only 1/7-order spots were visible, but a full 7×7 LEED pattern was not observed until cleavage above 710°C. The results provide evidence about surface structure stability and transitions.