Nucleation of Ge clusters at high temperatures on Ge/Si(001) wetting layer

Abstract

Listen

Translate article

Difference in nucleation of Ge quantum dots during Ge deposition at low (<600 °C) and high (≳600 °C) temperatures on the Si(001) surface is studied by high resolution scanning tunneling microscopy and in situ reflected high-energy electron diffraction. Two processes resulting in appearance of {105}-faceted clusters on the Ge wetting layer have been observed at high temperatures: Pyramids have been observed to nucleate via the previously described formation of strictly determined structures, resembling blossoms, composed by 16 dimers grouped in pairs and chains of 4 dimers on top of the wetting layer M×N patches, each on top of a separate single patch, just like it goes on at low temperatures; an alternative process consists in faceting of shapeless heaps of excess Ge atoms which arise in the vicinity of strong sinks of adatoms, such as pits or steps. The latter process is not observed at low temperatures; it is typical only for the high-temperature deposition mode.