ABSTRACT
One of the major factor that limit the performance and reliability of GaN high-electron-mobility-transistors (HEMTs) for high-power radio-frequency (RF) applications is their relatively high gate leakage current which reduces the breakdown voltage and the power-added efficiency whileincreasing the noise figure (NF). In order to suppress the gate leakage current, the metal–insulator–semiconductor (MIS) structure can be introduced to the GaNHEMT gate to form the MIS-HEMT. Since a broad category of insulation dielectrics for semiconductor devices includes oxides, the insulated gate is mostly of the metal–oxide–semiconductor (MOS) structure, thusforming the MOS-HEMT. In this chapter, all the HEMTs with oxide as the gatedielectric are referred to as MOS-HEMTs, with MIS-HEMTs as the general designationof insulated-gate HEMTs. Experiments indicate that GaN MOS-HEMTscan improve the gate voltage swing, microwave power performance, and long-termreliability. A brief introduction of GaN MOS-HEMTs with different structures, differentgate material system along with the differentDC and RF performance of MOS-HEMTare given in this chapter.
