Estructura (4$\times $3) inducida por la adsorción de los metales del grupo III sobre la superficie (001) del silicio

Abstract

A comparative study of the (4$\times $3) structure induced by the adsorption of group III metals (In, Al and Ga) on Si(001)-(4x3) is performed using first principles total energy calculations. The study corresponds to the deposition of metals at high temperature. Different models have been used to investigate the surface reconstructions and it has been found that the one proposed by Bunk et al. yielded the most stable configuration for all three cases. The structure showed the formation of pyramid-like metal-subunits with a trimer on top of it. This is composed of a Si atom occupying the highest vertical position and bound to two metal atoms with lower vertical positions. For the case of In, calculated bond lengths according to Bunk's model are similar to the sum of covalent radii. This is not the case of Al and Ga, explaining the experimental results showing that the (4$\times $3) structure remains as the stable structure at full In coverage, while for Ga and Al become (8$\times $5) and c(4$\times $2n), respectively.