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

Abstract

AbstractA 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 BaTiO3 as a “weak” ferroelectric gate in conjunction with a conventional SiNx dielectric. An enhancement in the capacitance for BaTiO3/SiNx gate stacks is observed in comparison to control structures with SiNx gate dielectrics directly indicating the negative capacitance contribution of the ferroelectric BaTiO3 layer. A significant reduction in the minimum subthreshold slope for the NC‐HEMTs is obtained in contrast to standard metal‐insulator‐semiconductor HEMTs with SiNx gate dielectrics—97.1 mV dec−1 versus 145.6 mV dec−1—with almost no hysteresis in the ID–VG 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.