I found a photo in my grandfather's effects that I believe to be of an RF GaAs FET. He was working in a GaAs FET lab at the time this photo was dated (1975). It was labeled on the back "300μm gate width on mesa".
I believe it was related to US Patent US4160984A filed in 1977; he is listed as one of the inventors.
The structure is foreign to me; where are the gate, source, and drain? Any additional information on the structure would be appreciated.
Best Answer
Here's an annotated version of what is what, from my experience laying out GaAs and GaN HEMTs:
You can see the gate finger peeling off of either side of the two gate contacts if you look closely. I can't tell which side is drain, which side is source, but if it's a symmetric device, they aren't any different physically (e.g. a FET designed for switch applications). My guess is that the dashed-line box is the mesa region.
Very cool photo and background :)