Small Vth Shift and Low Dynamic RON in GaN MOSHEMT With ZrO2 Gate Dielectric

The OFF-state stress-induced threshold voltage (Vth) instability and dynamic ON-resistance (RON) of GaN metal-oxide-semiconductor high-electron mobility transistor (MOSHEMT) with ZrO2 gate dielectric are thoroughly investigated. Upon negative gate bias stressing, a small threshold voltage shift of -0.31 V is observed and the deviation is attributed to the emission of electrons at the ZrO2/AlGaN interface. An emission activation energy of 0.28 eV and a capture activation energy of 0.30 eV are extracted by threshold voltage transient spectroscopy performed at various temperatures. When the device is exposed to OFF-state drain-source bias stressing, the drain current is found to decrease despite negative shift of Vth. A low dynamic R-ON of 2.05 is obtained by time-resolved measurements, given a 50-V drain voltage stressing for a duration of 100 s. The decrease in forward conductance is related to the capture of electrons in the access region, with a capture activation energy of 0.18 eV revealed by temperature-dependent drain current transient (DCT) analysis. The results indicate that high-quality ZrO2 represents an attractive high -k gate dielectric option for GaN MOSHEMTs in power switching electronics.

Automated summary

The OFF-state stress-induced threshold voltage instability and dynamic ON-resistance of GaN MOSHEMT with ZrO2 gate dielectric are investigated. Electron emission at the ZrO2/AlGaN interface is found to cause the threshold voltage shift. The activation energies of emission and capture are extracted by threshold voltage transient spectroscopy. Under OFF-state drain-source bias stressing, the drain current decreases despite the negative shift of threshold voltage, which is related to electron capture in the access region. The results suggest that high-quality ZrO2 is an attractive option for the gate dielectric of GaN MOSHEMTs in power switching electronics.