Andy,

I can't say I have done this before, but you may find Di : H2O2 : H3PO4
(1:4:3) will work for you @ 38 degrees.

I do it mechanically as I can't have anything happen to my front side.

Brent

Andy Irvine wrote:
> Hi all.
>
> Apologies for joining in order to ask a question - very bad form.  I
> promise to answer at least one myself!  Anyway...
>
> Any good tips for roughening a GaAs surface?
>
> I'm working with a GaAs(-based) wafer with (curses!) a polished back
> face, and am trying to avoid the possibility of multiple optical
> reflections between the two faces of the wafer.  I therefore need my
> back surface to be rough (in fact, just like any old one-side-polished
> substrate!).  I'd guess that it's going to involve mechanical abrasion
> followed by a preferential etch, but if anyone can be more specific and
> save me time (and ideally give me a good chemical-only HF-free method,
> please Santa), that'd be extremely helpful.
>
> I've blackened many a surface in my time, but it's remarkably hard to do
> it when you actually want to... ;-)
>
> Cheers,
>
> Andy