摘要
The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is observed that the threshold voltage shows a significant negative shift during the typical long-term on-state gate overdrive stress. The degradation does not originate from the presence of as-grown traps in the Al Ga N barrier layer or the generated traps during fluorine ion implantation process. By comparing the relationships between the shift of threshold voltage and the cumulative injected electrons under different stress conditions, a good agreement is observed. It provides direct experimental evidence to support the impact ionization physical model, in which the degradation of E-mode HEMTs under gate overdrive stress can be explained by the ionization of fluorine ions in the Al Ga N barrier layer by electrons injected from 2DEG channel.Furthermore, our results show that there are few new traps generated in the Al Ga N barrier layer during the gate overdrive stress, and the ionized fluorine ions cannot recapture the electrons.
The degradation mechanism of enhancement-mode Al Ga N/Ga N high electron mobility transistors（HEMTs） fabricated by fluorine plasma ion implantation technology is one major concern of HEMT＇s reliability. It is observed that the threshold voltage shows a significant negative shift during the typical long-term on-state gate overdrive stress. The degradation does not originate from the presence of as-grown traps in the Al Ga N barrier layer or the generated traps during fluorine ion implantation process. By comparing the relationships between the shift of threshold voltage and the cumulative injected electrons under different stress conditions, a good agreement is observed. It provides direct experimental evidence to support the impact ionization physical model, in which the degradation of E-mode HEMTs under gate overdrive stress can be explained by the ionization of fluorine ions in the Al Ga N barrier layer by electrons injected from 2DEG channel.Furthermore, our results show that there are few new traps generated in the Al Ga N barrier layer during the gate overdrive stress, and the ionized fluorine ions cannot recapture the electrons.
基金
Project supported by the National Natural Science Foundation of China(Grant Nos.61334002,61106106,and 61474091)
the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory(Grant No.ZHD201206)
the New Experiment Development Funds for Xidian University,China(Grant No.SY1213)
the Scientific Research Foundation for the Returned Overseas Chinese Scholars
