Surface morphology and growth mechanism upon condensation of As 4 and Sb 4 on arsenic and antimony (111) surfaces

Abstract

Shallow, triangular hillocks form when Sb 4 from a source at 600°C condenses on Sb (111) surfaces at ~580°C. Upon subsequent vaporization, oppositely oriented tringular pits appear, many at the apices of hillocks. A variety of growth features, including triangular hillocks, are observed when As 4 beams are condensed upon cleaved As (111) surfaces in ultrahigh vacuum. The features indicate a change in arsenic growth mechanism, with increasing substrate temperature and incident flux, from As 4 agglomeration to dislocation growth to island growth. Hillocks on arsenic and antimony appear to grow by a dislocation growth process which is the microscopic reverse of pit formation upon vaporization. The slopes of hillocks and of pits may be related by considering the effect of surface over-and undersaturation on spiral ledge spacings near dislocation cores.