No abstract

Pulse behavior of insulated-gate double-field-plate power AlGaN/GaN HEMTs with C-doped buffers showing small current-collapse effects and dynamic RDS,on increase can accurately be reproduced by numerical device simulations that assume the CN-CGa autocompensation model as carbon doping mechanism. Current-collapse effects much larger than experimentally observed are instead predicted by simulations if C doping is accounted by dominant acceptor states. This suggests that buffer growth conditions favoring CN-CGa autocompensation can allow for the fabrication of power AlGaN/GaN HEMTs with reduced current-collapse effects. The drain-source capacitance of these devices is found to be a sensitive function of the C doping model, suggesting that its monitoring can be adopted as a fast technique to assess buffer compensation properties

No abstract

No abstract

This paper investigates the degradation of GaN-based HEMTs with p-type gate submitted to positive gate bias stress. Based on combined electrical and optical testing, we demonstrate the existence of different degradation processes, depending on the applied stress voltage V Gstress : 1) for V Gstress < 7 V, no significant degradation is observed, thus demonstrating a good stability of the analyzed technology; 2) for 7 V < V Gstress < 11.5 V, a negative shift in threshold voltage (V th ) is observed, well correlated with a decrease in the gate leakage current and of the luminescence signal associated with hole injection. The negative V th shift is ascribed to the trapping of holes in the AlGaN and/or p-GaN/AlGaN interface; and 3) for V Gstress ≥ 12 V, threshold voltage recovers its initial value. This is ascribed to a net-negative charge, generated either by the trapping of electrons injected from the 2-D electron gas to the AlGaN or to the de-trapping of the holes injected in 2). The results described within this paper provide relevant information for understanding the degradation dynamics of normally off GaN transistors submitted to extremely high gate voltage levels far beyond maximum use.