High-k praseodymium oxide passivated AlGaN/GaN MOSFETs using P_2S_5/(NH_4)_2S_x + UV interface treatment

摘要

This study elucidates the praseodymium oxide (Pr_2O_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 P_2S_5/(NH_4)_2S_x + ultraviolet (UV) illumination. An electron-beam evaporated Pr_2O_3 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 P_2S_5/(NH_4)_2Sx solution and UV illumination before the gate insulator (Pr_2O_3) was deposited. Since stable sulfur that is bound to the Ga species can be efficiently obtained and surface oxygen atoms were reduced by P_2S_5/(NH_4)_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 Pr_2O_3, high-k AlGaN/GaN MOS-HEMTs, under P_2S_5/(NH_4)_2Sx + UV illumination treatment are suited to low-noise applications because of its electron-beam-evaporated insulator and the new chemical pretreatment.