Device characterization of p-channel AlGaAs/GaAs MIS-like heterostructure FET´s

p-channel 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 dtbetween the channel and metal gate, at low gate voltages. A high transconductance gmof 110 ms. mm-1is obtained at 77 K by reducing dtto 20 nm. Maximum transconductance is limited by gate-source leakage current Igs. Igsis 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 × 10¹³cm^-2. The contact resistance is reduced to about 0.1 ω. mm by ion implantation into the ohmic contact region to a dose of 2 × 10¹⁴cm^-2. Calculations indicate that, by reducing Igsand the gate-source resistance to 1 ω. mm with the lightly doped drain (LDD) structure, gmaround 200 mS. mm^-1at 300 K and 300 mS. mm^-1at 77 k are achievable with a 1-µm gate structure.