Formation of self-assembled Ge islands on Si (100) using magnetron sputtering and subsequent rapid thermal annealing

Abstract

Formation of Ge island after an ex-situ thermal annealing of Ge-rich film on Si (100) were investigated. Ge film was deposited using radio-frequency magnetron sputtering with the substrate being at room temperature. The film was then thermal annealed at an elevated temperature using a rapid thermal processor (RTP) in nitrogen ambient. The structural changes of the annealed film were studied using atomic force microscopy (AFM). Following annealing at temperature above 500oC, island assembling from Ge film were observed. The size of these islands were about 80-180nm wide 4-30nm in height. Density of the islands increases as annealing temperature increases up to 700oC. The surface morphology of the samples after annealing varies with various thickness of the Ge layer deposited on Si (100). The formation of the island was explained to form via the same mechanism as Stranski-Krastanov mode though it is not epitaxially grown. The high temperature annealing causes the adatoms to migrate and forms to islands as to minimize the surface energy.