Trapping effects in Al2O3/AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistor investigated by temperature dependent conductance measurements

Frequency dependent conductance measurements at varied temperature between 25 and 260 °C were performed to analyze trapping effects in the Al2O3/AlGaN/GaN metal-oxide-semiconductor heterostructure field-effect transistors. The trap states with a time constant τT,f≅(0.1–1) μs (fast) and τT,s=10 ms (slow) were identified. The conductance measurements at increased temperatures made it possible to evaluate the fast trap states in about a four times broader energy range than that from room temperature measurement. The density of the fast traps decreased from 1.4×1012 cm−2 eV−1 at an energy of 0.27 eV to about 3×1011 cm−2 eV−1 at ET=0.6 eV. The density of the slow traps was significantly higher than that of the fast traps, and it increased with increased temperature from about 3×1012 cm−2 eV−1 at 25–35 °C to 8×1013 cm−2 eV−1 at 260 °C.