High-k praseodymium oxide passivated AlGaN/GaN MOSFETs using P ₂S₅/(NH₄)₂S_X + UV interface treatment

This study elucidates the praseodymium oxide (Pr₂O ₃)-passivated AlGaN/GaN metal-oxide-semiconductor high electron mobility transistors (MOS-HEMTs) with high dielectric constant, and with their AlGaN Schottky layers treated with P₂S₅/(NH ₄)₂S_X + ultraviolet (UV) illumination. An electron-beam evaporated Pr₂O₃ insulator is used, instead of traditional plasma-assisted chemical vapor deposition (PECVD), to prevent plasma-induced damage on AlGaN. In this work, the HEMTs were pretreated by P₂S₅/(NH₄)₂S_X solution and UV illumination before the gate insulator (Pr₂O₃) was deposited. Since stable sulfur that is bound to the Ga species can be efficiently obtained and surface oxygen atoms were reduced by P ₂S₅/(NH₄)₂S_X pretreatment, the lowest leakage current was observed in MOS-HEMT. Additionally, a low flicker noise and a low surface roughness (1.1 nm) were also obtained using this novel process, to demonstrate its ability to reduce the surface states. Low gate leakage current Pr₂O₃, high-k AlGaN/GaN MOS-HEMTs, under P₂S₅/(NH₄)₂S _X + UV illumination treatment are suited to low-noise applications because of its electron-beam-evaporated insulator and the new chemical pretreatment.