电子辐照对AlGaN/GaN HEMT器件电特性的影响

Effects of Electron Radiation on Al Ga N / Ga N HEMT Electrical Properties

采用能量为1 Me V的电子对几种不同结构的Al Ga N/Ga N HEMT器件进行了最高注量为8.575×1014cm-2的辐照。实验发现:电子辐照后,最高注量下器件欧姆接触性能也几乎没有退化。辐照后未钝化器件的正反向栅电流有所增加,而且肖特基势垒高度随着辐照注量的增加而降低。几种结构HEMT器件的辐照结果表明,电子辐照后只有未钝化器件的特性有所退化,随着辐照注量增加,器件漏电流和跨导下降越明显,而且线性区退化大于饱和区,而阈值电压变化很小。分析表明,HEMT器件参数性能退化的主要原因是栅源和栅漏间隔区辐照感生表面态负电荷的产生。此外实验结果也说明Si N钝化、MOS结构和场板结构都是很好的抗辐照加固的手段。

Al Ga N / Ga N HEMTs with different structures were irradiated with 1 Me V electron to fluences of 8. 575 × 1014cm- 2. The experiment show that after the electron radiation with the highest fluences,the ohmic contact is so relative robustness to electron. But after irradiation,either forward or reverse gate leakage current of the unpassivated HEMTs are increased,and the schottky barrier height decreases with the increase of the irradiation fluences. The irradiation results of several devices structures show that only unpassivated devices degrade after electron radiation. As the increase of the radiation fluences,both drain current and transconductance of the devices decrease distinctly, and the linear region dagradation more than the saturated region,while the threshold voltage of the devices is relatively unaffected. The analysis results show that the major reason for HEMTs parameters degradation is the creation of electronegative surface state charges in source-gate spacer and gate-drain spacer. These results reveal that the Si N passivation,field plate and MOS structures are effective reinforced approaches.