Multibias and thermal behavior of microwave GaN and GaAs based HEMTs

Multibias and thermal characterizations on 0.25 μm × (2 × 100) μm AlGaN/GaN/SiC HEMT and 0.5 μm × (2 × 100) μm AlGaAs/InGaAs pseudomorphic HEMT have carried out for the first time. Two competitive device technologies are investigated with the variations of bias and temperature in order to afford a detailed realization of their potentialities. The main finding includes the self heating effect in the GaN device, zero temperature coefficient points at the drain current and transconductance in the GaAs device. The thermal resistance R_TH of 7.1, 8.2 and 9.4 °C mm/W for the GaN device was estimated at 25, 75 and 150 °C respectively which are consistent with those found in the open literature. The temperature trend of the threshold voltage V_T, Schottky barrier height ϕ_b, sheet charge densities of two dimensional electron gas ns, and capacitance under the gate C_g are exactly opposite in the two devices; whereas the knee voltage V_k, on resistance R_on, and series resistance R_series are shows similar trend. The multi-bias and thermal behavior of the output current I_ds, output conductance g_ds, transconductance g_m, cut-off frequency f_t, maximum frequency f_max, effective velocity of electron, veff and field dependent mobility, μ demonstrates a great potential of GaN device. These results provide some valuable insights for technology of preference for future and current applications.