GaN-based high-k praseodymium oxide gate MISFETs with P₂S ₅/(NH₄)₂ S_X + UV interface treatment technology

This study examines the praseodymium-oxide- (Pr₂O₃-) passivated AlGaN/GaN metal-insulator-semiconductor high electron mobility transistors (MIS-HEMTs) with high dielectric constant in which the AlGaN Schottky layers are treated with P₂S₅/(NH ₄)₂ S X + ultraviolet (UV) illumination. An electron-beam evaporated Pr₂O₃ insulator is used instead of traditional plasma-assisted chemical vapor deposition (PECVD), in order to prevent plasma-induced damage to the AlGaN. In this work, the HEMTs are pretreated with P₂S₅/(NH₄)₂ S X solution and UV illumination before the gate insulator (Pr₂O₃) is deposited. Since stable sulfur that is bound to the Ga species can be obtained easily and surface oxygen atoms are reduced by the P₂S ₅/(NH₄)₂ S X pretreatment, the lowest leakage current is observed in MIS-HEMT. Additionally, a low flicker noise and a low surface roughness (0.38 nm) are also obtained using this novel process, which demonstrates its ability to reduce the surface states. Low gate leakage current Pr₂O₃ and high-k AlGaN/GaN MIS-HEMTs, with P ₂S₅/(NH₄)₂ S X + UV illumination treatment, are suited to low-noise applications, because of the electron-beam-evaporated insulator and the new chemical pretreatment.