Abnormal C-V Hump after Negative Bias Stress in GaN MIS High Electron Mobility Transistor (GaN MIS-HEMT)

Ya-Huan Lee^1*, Ting-Chang Chang², Yun-Hsuan Lin¹

¹Department of Physics, National Sun Yat-Sen University, Kaohsiung, Taiwan
²Department of Physics, and also with the Center of Crystal Research, National Sun Yat-Sen University, Kaohsiung, Taiwan

* Presenter:Ya-Huan Lee, email:alan310405@gmail.com

In this study, the electron injection to buffer layer causes positive threshold voltage shift and Ion degradation after negative bias stress on GaN Metal-Insulator-Semiconductor high electron mobility transistor (MIS-HEMT). An abnormal hump is also observed in the ID-VG curve. By utilizing C-V measurement, variable bias voltages and positive bias stress (PBS), the result shows that the abnormal phenomenon is related to the mesa isolation. Due to the uneven distribution of the electric field in the channel width direction below gate, electrons unevenly trapped into the buffer layer, and cause abnormal hump in the C-V curve. Finally, Silvaco TCAD simulation is used to further confirm this statement, and the physic model is proposed.

Keywords: MIS-HEMT, Negative Bias Stress, C-V Hump