It presents a complete set of device parameters variations with ambient temperature for two technologies: 0.5 μm × (2 × 100 μm) AlGaAs/InGaAs pseudomorphic HEMT and 0.25 μm × (2 × 100 μm) AlGaN/GaN/SiC HEMT. This includes experimental characterisations, modeling and analysis of these two devices over the ambient temperature from −40 to 150 °C.

Temperature coefficient along with thermal behavior of all the device parameters for both GaN and GaAs HEMTs providing a detailed insight of these two devices. These analyses are valuable for technology of choice for current and future applications.

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.

Most of these parameters show negative trend with temperature such as drain source output current I_ds, extrinsic transconductance g_m, intrinsic transconductance g_mo, output conductance g_ds, effective electron velocity v_eff, cut-off frequency f_t and maximum frequency f_max.

Meanwhile, the knee voltage V_k, on resistance R_on and series resistance R_series shows positive trend with temperature. Differences are observed most notably that the variation of 2-DEG sheet carrier density n_s, capacitance under the gate C_g, threshold voltage V_T and Schottky barrier height f_b with temperature are completely different for the two devices.