High-k praseodymium oxide passivated AlGaN/GaN MOSFETs using P2S5/(NH4)2SX + UV interface treatment

This study elucidates the praseodymium oxide (Pr2O3)-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/(NH4)2SX + 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)2SX 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 P2S5/(NH4)2SX 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)2SX + UV illumination treatment are suited to low-noise applications because of its electron-beam-evaporated insulator and the new chemical pretreatment.