Small info on Current GaAs technology needed

Hi all,
I need to know what is the current standard in the thickness of GaAs substrate used for MMIC design.Last , when I read , it was 500 micron,I am sure it has gone down by much.Can you please throw some light on this ?

Thank you

The most popular for microstrip is 4 mils (100 microns). For power there is also 2 mils. UMS has something between for high frequency (lower W band).
If you go on CPW then it might be 500 microns.