Effects of Nitride-Based Plasma Pretreatment Prior to SiN_x Passivation in AlGaN/GaN High-Electron-Mobility Transistors on Silicon Substrates

Abstract

The effects of nitride-based plasma pretreatment on the output characteristics of AlGaN/GaN high-electron-mobility transistors (HEMTs) on silicon substrates are investigated. N 2 and NH 3 plasma pre-treatment methods are studied to overcome the RF dispersion phenomenon caused by nitrogen-vacancy (V N )-related defect reduction. It is found that the nitride-based plasma pretreatment is effective to overcome the RF dispersion in AlGaN/GaN HEMTs on Si. The NH 3 plasma pretreatment markedly reduced RF dispersion from 63 to 1%. This is considered to be attributable to the reduction of the effective V N -related defect density and elimination of carbon/oxide residuals on the surface of AlGaN/GaN HEMTs. A NH 3 plasma pretreatment prior to SiN x 100 nm passivation in the AlGaN/GaN HEMTs on Si markedly improves the total output power from 15 to 18.1 dBm under the operating conditions of V DS = 15 V/ V GS = -1 V.