High-energy proton radiation for enhanced Cascode structural Gallium nitride power devices Effect studies

To investigate the damage mechanism caused by high-energy proton irradiation to AlGaN/GaN power devices of enhanced Cascode structures. For the enhanced Cascode structure and depletion AlGaN/GaN power devices, the radiation effect was studied using 60 MeV energy protons in this artical. In the case of proton injection reaching 1×10¹² p·cm^-2, the experimental results show that the threshold voltage of the Cascode type devices is negative drift, the transconductance is reduced, and the mountain leakage current is increased. The threshold voltage was reduced from 4.2 V to 3.0 V, drifting 1.2 V; The peak transconductance value decreased from 0.324 S·mm^-1 to 0.260 S·mm^-1, a decrease of about 19.75%. There is no significant change after irradiation of conventional depleted AlGaN/GaN devices. The Cascode type AlGaN/GaN power devices are more sensitive to proton irradiation than the depletion type AlGaN/GaN devices. The Cascode-type devices are sensitive to proton irradiation because of its structure connected to a silicon-based MOS tube. Proton irradiation causes the silicon-based MOS gate oxide layer to generate a large amount of net positive charge, induces ionization damage effect, and causes negative drift of threshold voltage and increase of gate leakage current. The equivalent, 60 MeV energy protons and cumulative injection of 1×10¹² p·cm^-2 dose of the ⁶⁰Coγ radiation device is used to obtain the ionization damage effect. It was found that after the equivalent dose ⁶⁰Coγ ray irradiation, the threshold voltage of the device was reduced from 4.15 V to 2.15 V, and the negative drift was 2 V; Transconductance peak from 0.335 S·mm^-1 to 0.300 S·mm^-1, reducing by approximately 10.45%. The degradation of the electrical properties of the device after ⁶⁰Coγ ray irradiation is consistent with the degradation law after irradiation of high-energy protons. In order to further verify the accuracy of the experiments and conclusions, the ionization energy loss and non-ionization energy loss induced by radiation in the device are obtained by Monte Carlo simulation. The simulation results show that ionization energy loss induces silicon-based MOS to generate oxide trap charge and interfacial state trap charge, which is the main reason for the performance degradation of AlGaN/GaN HEMT power devices with enhanced Cascode structure.