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