Preparation of clean and atomically flat germanium(001) surfaces

A two-part procedure for preparing clean and atomically flat Ge(001)-(2 x 1 ) surfaces is presented and characterized. The ex situ part of the procedur e consists of a wet chemical treatment followed by exposure to ultraviolet- generated ozone. The in situ part of the procedure consists of outgassing f or several hours in ultrahigh vacuum followed by flash annealing. Scanning tunneling microscopy shows that the surfaces are flat on the >50 nm length scale and that atomic resolution can be achieved. X-ray photoelectron spect roscopy shows the formation and removal of an oxide layer. It is estimated that approximately 0.02-0.03 monolayers of carbon are present at the anneal ed surface. (C) 1999 Elsevier Science B.V. All rights reserved.