Abstract
A high quality SiO2 deposition process using a plasma enhanced chemical vapor deposition system has been developed for the gate insulator process of normally-off recessed-gate AlGaN/GaN metal–oxide–semiconductor-heterostructure field-effect transistors (MOS-HFETs). SiO2 films were deposited by using SiH4 and N2O mixtures as reactant gases. The breakdown field increased with increasing the N2O flow rate. The optimum SiH4/N2O ratio was 0.05, which resulted in a maximum breakdown field of 11MV/cm for the SiO2 film deposited on recessed GaN surface. The deposition conditions were optimized as follows; a gas flow rate of SiH4/N2O (=27/540sccm), a source RF power of 100W, a pressure of 2Torr, and a deposition temperature of 350°C. A fabricated normally-off MOS-HFET exhibited a threshold voltage of 3.2V, a specific on-resistance of 4.46mΩcm2, and a breakdown voltage of 810V.
Published Version
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