Investigation of In Situ NH₃ and N₂O Plasma Treatment on AlGaN/GaN High Electron Mobility Transistors

Plasma pre-treatment using NH 3 and N 2 O gases was conducted prior to deposition of a SiN passivation layer to compare and analyze the impact of each plasma gas on the device characteristics of AlGaN/GaN high electron mobility transistors (HEMTs).Surface analyses were performed through atomic force microscopy, X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy.A systematic investigation confirmed improvements in surface quality, with the most significant enhancement observed after NH 3 plasma treatment.In particular, XPS analysis provided insights into these improvements, highlighting the effective oxide removal capability of NH 3 plasma.Additionally, direct current and frequency dispersion analyses through capacitance measurements confirmed that the device characteristics were enhanced after plasma treatment.The plasma treatment using NH 3 gas thus was very effective for improving the surface quality in AlGaN/GaN HEMTs.