Key Technology Research Of GaN Based Metal-ferroelectric-semiconductor Field Effect Transistor

Metal-insulator-semiconductor field effect transistor based on Gallium nitride (GaN) is a very promising candidate device, the dielectric of gate is one attractive field, all of these structures are fabricated with conventional oxides, like SiO25SiN et al. as insulators. GaN MOSFET has large applied voltage due to low permittivity. The applied voltage is higher than 15V. therefore the limit of process is challenged for decreasing the applied voltage, such as minishing the thickness of insulators, however the effect of quantum will be greatly serious with the decrease of insulator thickness when the scale of device come into deep sub-micro region, the tunneling current will become enormous, and the power consumption is enhanced, the new material with high permittivity must be found, the ferroelectric material is a excellent candidate with modulated permittivity. In addition it is compatible with integrated circuit technology. Among the ferroelectric materials ,lead zirconate titanate( PbZrxTi1-xO3, PZT) is studied widely and deeply. Especially in the memories and sensors .Various techniques are available for the fabrication of PZT thin film.such as Sol-Gel, sputtering, MOCVD, PLD and MBE methods, the Sol-Gel method is adopted for its simplicity and compatibility with IC techniques, the raw materials are lead acetate trihydrate [ Pb(OCOCH3)2.3H2O], Zirconium nitrate [Zr(NO3)4.5H2O] and tetrabutyl titanate [Ti(OC4H9)4]. Ethyllene glycol monomethyl ether is the solvent. Because zirconium alkoxide is relatively expensive. Further domestics can not supply it. So Zirconium nitrate is adopted. Based on fabrication of PZT thin film,Si and GaN MFS structure is made,and the capacitance and voltage curve is tested, on the other hand, the model of threshold voltage and of C-V is given. Simulation is done .All of these prove that the applied voltage can be decreased when utilizing PZT as gate dielectric.It provide a approach of low voltage GaN-MISFET and HEMT.