This study examines the praseodymium-oxide- (Pr2O3-) passivated AlGaN/GaN metal-insulator-semiconductor high electron\r\nmobility transistors (MIS-HEMTs) with high dielectric constant in which the AlGaN Schottky layers are treated with\r\nP2S5/(NH4)2SX + ultraviolet (UV) illumination. An electron-beam evaporated Pr2O3 insulator is used instead of traditional\r\nplasma-assisted chemical vapor deposition (PECVD), in order to prevent plasma-induced damage to the AlGaN. In this work,\r\nthe HEMTs are pretreated with P2S5/(NH4)2SX solution and UV illumination before the gate insulator (Pr2O3) is deposited. Since\r\nstable sulfur that is bound to the Ga species can be obtained easily and surface oxygen atoms are reduced by the P2S5/(NH4)2SX\r\npretreatment, the lowest leakage current is observed in MIS-HEMT. Additionally, a low flicker noise and a low surface roughness\r\n(0.38 nm) are also obtained using this novel process, which demonstrates its ability to reduce the surface states. Low gate leakage\r\ncurrent Pr2O3 and high-k AlGaN/GaN MIS-HEMTs, with P2S5/(NH4)2SX + UV illumination treatment, are suited to low-noise\r\napplications, because of the electron-beam-evaporated insulator and the new chemical pretreatment.
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