Demonstration of Wide Bandgap AlGaN/GaN Negative‐Capacitance High‐Electron‐Mobility Transistors (NC‐HEMTs) Using Barium Titanate Ferroelectric Gates

Abstract A negative‐capacitance high electron mobility transistor (NC‐HEMT) with low hysteresis in the subthreshold region is demonstrated in the wide bandgap AlGaN/GaN material system using sputtered BaTiO 3 as a “weak” ferroelectric gate in conjunction with a conventional SiN x dielectric. An enhancement in the capacitance for BaTiO 3 /SiN x gate stacks is observed in comparison to control structures with SiN x gate dielectrics directly indicating the negative capacitance contribution of the ferroelectric BaTiO 3 layer. A significant reduction in the minimum subthreshold slope for the NC‐HEMTs is obtained in contrast to standard metal‐insulator‐semiconductor HEMTs with SiN x gate dielectrics—97.1 mV dec −1 versus 145.6 mV dec −1 —with almost no hysteresis in the I D – V G transfer curves. These results are promising for the integration of ferroelectric perovskite oxides with III‐Nitride devices toward NC‐field‐effect transistor switches with reduced power consumption.