Hello all, I have been testing on wet etching of sapphire using H3PO4 and H2SO4 (Thanks for early posts on this list!). It looks like that this mixture can etch sapphire at high temperature (>300C). However, since I have the device (GaN based) grown on the other side of the sapphire, I need to find a way to protect it temporarily - so far not succeeded! Anyone has any suggestions? Thanks, Kai --------------------------------- Do you Yahoo!? Yahoo! Mail - 50x more storage than other providers!