Effect of Si-rich SiXNY multilayer passivation material on the DC electrical characteristics of AlGaN/GaN HEMTs

In this study, the effect of SiXNY bilayer passivation materials on the electrical properties of an AlGaN high electron mobility transistor (HEMT) was investigated. AlGaN/GaN HEMTs were grown on 3-inch silicon carbide by the metal organic chemical vapor deposition method, which is one of the chemical vapor deposition methods. SiXNY passivation materials with two different Si concentrations, which were 50/1 and 70/3 (Silane-SiH4/Ammonia-NH3), were used. The passivation material coating process was carried out with the plasma enhanced chemical vapor deposition (PECVD) system. The first sample was a coated single layer with 70/3 (SiH4/NH3) passivation material at 75 nm and the second sample was coated with bilayer (two layers) passivation materials wherein the first layer was coated with 15 nm 50/1 (SiH4/NH3) and the second layer was coated with 60 nm 70/3 (SiH4/NH3). The obtained results were compared. Experimental results show that the drain leakage current (I-d) and gate leakage current (I-g) decreases; current density (I-dss) and transconductance (g(m)) increases with bilayer passivation.