Study On The AlGaN/GaN MOS-HEMT Device With High-κ Materials As Gate Dielectric

The device of GaN HEMT has the advantages of a wide bandgap, large density of2DEG, high mobility of the electron and breakdown voltage, so it has a great superiorityin the application of the high microwave power device.In order to reduce the gate leakage current, the mos-structure is added to the GaNdevice. With the scale of the device into Nano-level, the traditional mos-structure withthe SiO₂as its gate dielectric material will face the problem of its performancedegradation caused by the tunneling effect. So the AlGaN/GaN MOS-HEMT devicewith the high-κ material as its gate dielectric material is widely studied.An AlGaN/GaN MOS-HEMT device with HfO₂as its gate dielectric material isbuilt by using ISE-TCAD. Firstly, a study of the effect of the Al composition orthickness of the AlGaN layer on the density of the2DEG is made by simulation withISE. Secondly, the device characteristics, such as transfer characteristics, transconduct-ance, output characteristics, the breakdown voltage of the device, and the capacitanceon low frequency, are studied by simulation. Finally, the effects of different conditionson the DC characteristics of the device are studied and analyzed in this paper.The effects of different pulse conditions on the current collapse of the MOS-HEMT device with high-κ gate dielectric are also studied by simulation. And then, theinhibition measures on the current collapse are studied and simulated by ISE. Firstly,different materials such as SiN, HfO₂and SiO₂are added to devices as passivationmaterials, respectively, and then the current collapse of these devices are simulated andcompared. Finally, a device with SiN as passivation material and the field platestructure is built and the effect of the uniform gate field plate structure on the currentcollapse is studied. All of the mechanisms of the inhibition measures on the currentcollapse are analyzed, respectively.