Characterization of stress degradation effects and thermal properties of AlGaN/GaN HEMTs with photon emission spectral signatures

The influence of stress degradation and device temperature variation on the device properties has been investigated with electrical and photon emission (PE) measurements. To degrade the devices the type of short-time stress tests, namely DC-Step-Stress-Tests of GaN HEMTs have been performed on wafers with and without GaN cap to additionally check the behaviour of various technological processes. It has been found that wafers with GaN cap show much higher critical voltages as compared to non-capped epitaxial designs and have different PE spectral signatures. Thermo-electrical topics like high power dissipation and self-heating of GaN based HEMTs were also investigated with electrical characterization and electroluminescence in various operating conditions.