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采用不同的高场应力和栅应力对AlGaN/GaN HEMT器件进行直流应力测试,实验发现:应力后器件主要参数如饱和漏电流,跨导峰值和阈值电压等均发生了明显退化,而且这些退化还是可以完全恢复的;高场应力下,器件特性的退化随高场应力偏置电压的增加和应力时间的累积而增大;对于不同的栅应力,相对来说,脉冲栅应力和开态栅应力下器件特性的退化比关态栅应力下的退化大.对不同应力前后器件饱和漏电流,跨导峰值和阈值电压的分析表明,AlGaN势垒层陷阱俘获沟道热电子以及栅极电子在栅漏间电场的作用下填充虚栅中的表面态是这些不同应力下器件退化的主要原因.同时,不同栅应力下器件的退化表明,钝化只是把短时间的电流崩塌问题转化成了长时间的退化问题,它并不能从根本上完全解决AlGaN/GaN HEMT的可靠性问题.
The DC stress of AlGaN / GaN HEMT devices is tested by different high field stress and gate stress. The experimental results show that the main parameters of the devices such as saturation leakage current, transconductance peak and threshold voltage are significantly degraded after stress, and these degenerations are still Can be fully restored; under high field stress, the degradation of device characteristics increases with the increase of high field stress bias voltage and the accumulation of stress time; for different gate stress, relatively, the gate pulse stress and open gate stress The degradation of the device characteristics is larger than the degradation under the off-state gate stress.The analysis of saturation leakage current, transconductance peak and threshold voltage before and after different stress shows that trapped channel hot electron and gate electron gate in gate The surface state in the filled dummy gate under the inter-leakage electric field is the main reason of device degeneration under these different stresses.At the same time, the degradation of devices under different gate stresses shows that passivation only transforms the short-time current collapse problem into a long time It can not fundamentally solve the reliability problem of AlGaN / GaN HEMT completely.