Emitter Turn off??
I have head of GTO's (Gate Turn-Off) but never ETO's
--EDIT--
ahh I see.
No such device as ETO, but it is a control strategy.
a GTO in series with a suitable FET, thus this fwd current is used to turn the GTO off, since you can now get 1x the current the GTO will turn off faster then usual (normal turn-off method is to achive by drawing 1/3 of the fwd current from the gate)
trying to fit into the region where IGBT's cant fit (higher power) and where Thyristors/GTO cant (higher switching freq)
interesting