AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors(MIS-HEMTs) on a silicon substrate were fabricated with silicon oxide as a gate dielectric by sputtering deposition and electron-beam(EB) eva...AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors(MIS-HEMTs) on a silicon substrate were fabricated with silicon oxide as a gate dielectric by sputtering deposition and electron-beam(EB) evaporation. It was found that the oxide deposition method and conditions have great influences on the electrical properties of HEMTs. The low sputtering temperature or oxygen introduction at higher temperature results in a positive equivalent charge density at the oxide/AlGaN interface(Nequ), which induces a negative shift of threshold voltage and an increase in both sheet electron density(ns) and drain current density(ID). Contrarily, EB deposition makes a negative Nequ, resulting in reduced ns and ID. Besides, the maximum transconductance(gm-max) decreases and the off-state gate current density(I_(G-off)) increases for oxides at lower sputtering temperature compared with that at higher temperature, possibly due to a more serious sputter-induced damage and much larger Nequ at lower sputtering temperature. At high sputtering temperature, I_(G-off) decreases by two orders of magnitude compared to that without oxygen, which indicates that oxygen introduction and partial pressure depression of argon decreases the sputter-induced damage significantly. I_(G-off) for EB-evaporated samples is lower by orders of magnitude than that of sputtered ones, possibly attributed to the lower damage of EB evaporation to the barrier layer surface.展开更多
Al/Ni films were deposited on 128° Y-X LiNbO3 substrates by e-beam deposition. The influence of Ni underlayer on the microstructure, adhesion and resistivity of the Al/Ni films was investigated. It was found that...Al/Ni films were deposited on 128° Y-X LiNbO3 substrates by e-beam deposition. The influence of Ni underlayer on the microstructure, adhesion and resistivity of the Al/Ni films was investigated. It was found that Al films deposited on Ni underlayer thinner than 5 nm possessed strong texture. The textured Al/Ni films had a superior adhesion. Their resistivity decreased after annealing treatment at 200℃ for 30 min. With the textured Al/Ni films, a 2,30 GHz-range image-impedance connection SAW （Surface Acoustic Wave） filter was successfully fabricated.展开更多
基金supported by the National Science Foundation of China(No.61504071)
文摘AlGaN/GaN metal–insulator–semiconductor high-electron-mobility transistors(MIS-HEMTs) on a silicon substrate were fabricated with silicon oxide as a gate dielectric by sputtering deposition and electron-beam(EB) evaporation. It was found that the oxide deposition method and conditions have great influences on the electrical properties of HEMTs. The low sputtering temperature or oxygen introduction at higher temperature results in a positive equivalent charge density at the oxide/AlGaN interface(Nequ), which induces a negative shift of threshold voltage and an increase in both sheet electron density(ns) and drain current density(ID). Contrarily, EB deposition makes a negative Nequ, resulting in reduced ns and ID. Besides, the maximum transconductance(gm-max) decreases and the off-state gate current density(I_(G-off)) increases for oxides at lower sputtering temperature compared with that at higher temperature, possibly due to a more serious sputter-induced damage and much larger Nequ at lower sputtering temperature. At high sputtering temperature, I_(G-off) decreases by two orders of magnitude compared to that without oxygen, which indicates that oxygen introduction and partial pressure depression of argon decreases the sputter-induced damage significantly. I_(G-off) for EB-evaporated samples is lower by orders of magnitude than that of sputtered ones, possibly attributed to the lower damage of EB evaporation to the barrier layer surface.
基金[This work was financially supported by the National High-technology Project of China (No. 2002AA325040), the National Natural Science foundation of China (No. 50325105, 50371040) and the Key Grant of Chinese Ministry of Education (No. 0303).]
文摘Al/Ni films were deposited on 128° Y-X LiNbO3 substrates by e-beam deposition. The influence of Ni underlayer on the microstructure, adhesion and resistivity of the Al/Ni films was investigated. It was found that Al films deposited on Ni underlayer thinner than 5 nm possessed strong texture. The textured Al/Ni films had a superior adhesion. Their resistivity decreased after annealing treatment at 200℃ for 30 min. With the textured Al/Ni films, a 2,30 GHz-range image-impedance connection SAW （Surface Acoustic Wave） filter was successfully fabricated.
