IIIB-1 degradation of 77-K MOSFET characteristics due to channel hot electrons

of 1 9 dB at 10 GHz and a maximum available gain of 1 1 c l 3 at 18 GHz. Extrapolation of this maximum available gain usi l g a 6 dB/octave rolloff yields a maximum frequency of oscilla ion (fmax) of 65 GHz, compared with 100 GHz for the best 'levices.' The OMCVD-overgrown devices have a lower f l,lax because their output impedance, as derived from an equiva cnt circuit model, is about an order of magnitude lower. Atten 11?ts are in progress t o fabricate PBT's with higher impedance ~ !,'or example, by reducing the doping of the overgrown GaAs 1a:er) without significantly degrading the other device parame1,ers. The performance of such devices would equal or exceed the best PBT performance so far achieved.