I have experience contacting to single crystal germanium that is 100 microns
thick, not evaporated germanium 0.2 microns thick, so I don't know if the same
thing will work.  But for what it is worth, we used sputtered gold Au with no
diffusion barrier or adhesion layer.  It helps to reverse sputter to clean the
Ge surface first.  No annealing is needed.  We also used electroplated gold, but
it was not quite as good.  This worked for making infrared detectors with
mercury doped germanium, and was a low noise contact down to 10 degrees Kelvin.

Zeng Wenjiang wrote:

> Can I get advice on the ohmic contact to evaporate Germanium ?   The
> Germanium is e-beam evaporated at thickness about 0.2 microns.  Which metal
> can be used for the contact ?  Is diffusion barrier required ? Is adhesion
> layer needed ? Any concerns or recommendations about electrical behavior and
> contact resistance ? Any anneal suggested ? Can anybody suggest some general
> references about this ?
>
> Thanks in advance.
>
> Zeng Wenjiang
> Research Engineer
> Institute of Microelectronics, Singapore.
> Fax: (65) 7770670
> wenjiang@ime.org.sg
>



--
John R. Karpinsky  ---  Chief Physicist
MEMS Optical, Inc., 205 Import Circle, Huntsville, AL 35806
Tel: 256-859-1886  Fax: 256-859-5890  Email: johnk@memsoptical.com