Temperature-dependent high-frequency performance of deep submicron AlGaN/GaN HEMTs

A study of the low temperature DC and RF performance of deep submicron AlGa N/GaN high electron mobility transistors (HEMTs) is reported. From 300 K to both extrinsic transconductance and drain current increase by similar to 30%, mainly due to the lowering of the optical phonon scattering that allows higher electron mobility. Source and drain resistances improve too, which contributes to the 15-20% increase of f(t) and f(max). The low temperature small signal model has also been extracted accurately at every 50 K. Inductances and capacitances remain constant in the range of temperatures measured. The intrinsic transconductance can be also considered temperature independent, but the output conductance decreases from 300 K to 100 K indicating a better confinement of the 2DHG. The HEMT performance obtained at 100 K can be reached at room temperature by reducing the parasitic resistances and improving the GaN buffer isolation. (C) 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.