Auger spectroscopy studies of the oxidation of amorphous and crystalline germanium

We have used Auger−electron spectroscopy and ion−beam etching to study the room−temperature oxidation of sputtered and electron−beam−evaporated Ge films. Both amorphous and polycrystalline films were examined, as well as single−crystal Ge. Electron−escape−depth effects were removed by a deconvolution procedure in order to obtain the O distribution function. Large differences of O distribution were found between sputtered and e−beam amorphous films. Sputtered amorphous films oxidize in the same manner as single−crystal Ge, with the O confined to the first 5−10 Å of the surface. In e−beam amorphous films, the depth of O penetration is more than 200 Å, although the heavily oxidized region is still only 10−12 Å thick. Polycrystalline films have heavily oxidized layers 6−9 Å thick, with some O present to a depth of 100−200 Å.