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In this paper we analyze the conduction properties, charge trapping and threshold voltage instability of normally-on β-Ga2O3 lateral MOSFETs for high power applications by means of threshold voltage transients. We found that a positive bias applied to the gate induces a rightward shift in the threshold voltage, caused by the trapping of electrons at border traps close to the semiconductor-dielectric interface. The amount of trapped charge was investigated by an innovative fast-CV experimental setup and was found to follow a logarithmic kinetic in time, modeled by a generalization of the inhibition model that takes into account the effect of columbic repulsion in stress conditions. Then, we developed a model for the gate conduction based on temperature dependent IG-VG characteristics. We detected that the gate current characterized in temperature and bias conditions similar to the ones used for the stress is dominated by Poole-Frenkel conduction assisted by a deep level at EC - 0.12 eV. |
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