EXCELLENT THERMALLY STABLE EPITAXIAL CHANNEL FOR IMPLANTED PLANAR-TYPE HETEROJUNCTION FIELD-EFFECT TRANSISTORS

We demonstrate for the first time that the decrease in the carrier con centration of highly doped GaAs layers caused by annealing is alleviat ed by thinning the lasers. It. is also suggested that the decrease is dependent on the Fermi energy in the doped lasers. Thermally stable th in Si-doped GaAs channels are formed in implanted planar-type two-mode channel field-effect transistors (P-TMTs). A 0.2-mu m device having a GaAs channel 9 nm thick with a doping level of 7 x 10(18) cm(-3) exhi bits excellent performance, such as a transconductance g(m) of 450 mS/ mm, a current-gain cutoff frequency f(T) of 72 GHz, and a maximum freq uency of oscillation f(max) of 140 GHz. Furthermore, it is indicated t hat highly doped thin lasers are very effective for improving the DC a nd microwave performance of P-TMTs.