Analysis of slow de-trapping phenomena after a positive gate bias on AlGaN/GaN MIS-HEMTs with in-situ Si_3N_4/Al_2O_3 bilayer gate dielectrics

摘要

We focus on slow de-trapping phenomena in AlGaN/GaN MIS-HEMTs with a bilayer dielectric (in-situ Si_3N_4/Al_2O_3) with two different thicknesses of in-situ Si_3N_4 (10 nm and 5 nm). By using a "filling pulse" at a positive gate voltage, a trap with activation energy of 0.69-0.7 eV was identified to be responsible for the V_(TH) shift. Based on literature, filling conditions, and the simulated band diagrams, this trap is most probably located at the interface between the dielectrics and AlGaN barrier. A physical model is proposed to explain the V_(TH) shift due to the trapping/de-trapping phenomena based on the occupation dynamics of donor traps at the interface between the in-situ Si_3N_4/Al_2O_3 and the AlGaN barrier.