The effect of mismatch strain on Stranski-Krastanow transition in epitaxial Ge_xSe_1-x/Si(0 0 1) gas-source growth

摘要

Mechanisms of strain-relife during epitaxial growth of Ge_0.6Si_0.4/Si(0 0 1) alloy at 500 deg C have been investigated using in situ scanning tunneling microscopy. The reduction of mismatch srain due to reduced Ge content of the epilayer (2.6/100 relative to 4.2/100 in Ge/Si(0 0 1)) has a profound effect not only on the final film morhology, but seem to alter the entire sequence of inermediate surface morphologies which, under these conditions, is domianted yb layer-mounding rather than by faceting. Low-angle facets ≈6 deg), different from the 11 deg -{5 0 1} facets in the case of pure Ge/Si(0 0 1), appear only at the final stages of growth. Understanding of roughening transitions in strained-laeyr growth is essential for controlling the clsuter size and geometry for applications in quantum dot devices.