Was looking up patents,came across this one,no mention of GaAs but patent seems to be just for a Thyristor memory cell IC.i am not an electronics guy but Some of the literature sounds like some of the stuff i keep hearing from GT-

The thyristor devices of the memory cells of the array can be realized from an epitaxial layer structure formed on the substrate that defines complementary n-type and p-type modulation doped quantum well interfaces. The epitaxial layer structure can include an N+ type doped layer, a first plurality of layers forming a p type modulation doped quantum well interface spaced from the N+ type doped layer, a second plurality of layers forming an n-type modulation doped quantum well interface, the first plurality of layers being separated from the second plurality, and a P+ type doped layer spaced from the second plurality of layers. The n-type modulation doped quantum well interface includes at least one quantum well separated from an n-type doped charge sheet by at least one undoped spacer layer. The p-type modulation doped quantum well interface includes at least one quantum well separated from a p-type doped charge sheet by at least one undoped spacer layer. The p-type modulation doped quantum well interface can be formed above the N+ type doped layer.

Full Patent

file:///C:/Users/Dell/Downloads/US2014047128%20THYRISTOR%20MEMORY%20CELL%20INTEGRATED%20CIRCUIT.html