p-chanhel AlGaAs/GaAs MIS-like heterostructure FET's (p-MIS HFET's) are characterized concerning their gate-source leakage current. Device performance is confirmed to improve approximately inversely to layer thickness dt, between the channel and metal gate, at low gate voltages. A high transconductance gm of 110 ms. mm-1 is obtained at 77 K by reducing dt to 20 nm. Maximum transconductance is limited by gate-source leakage current Igs. lgs is governed mainly by the leakage current through the ion-implanted gate edge and is reduced by decreasing the dose level of ion implantation at the gate edge to 2 x 1013 cm-2. The contact resistance is reduced to about 0.Ω1 mm by ion implantation into the ohmic contact region to a dose of 2 x 1014 cm-2. Calculations indicate that, by reducing fgs and the gate-source resistance to 1Ωmm with the lightly doped drain (LDD) structure, gm around 200 mS- mm-1 at 300 K and 300 mS - mm-1 at 77 k are achievable with a[fprmula ommitet] gate structure.
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