Stability and robustness of InAlGaN/GaN HEMT in short-term DC tests for different passivation schemes.

On-wafer short term step-stress tests were carried out to evaluate InAlGaN/GaN HEMT devices. Three types of transistor were studied, each one having a specific two dielectric layer passivation. The results of these tests demonstrate that the upper layer of the passivation has a strong impact on the ageing of the devices. When the upper layer is an Al2O3 Atomic Layer Deposited one, the transistors show a better stability of their electrical parameters than those passivated with the other stacks.