InGaAs Tunneling Field-Effect-Transistors With Atomic-Layer-Deposited Gate Oxides

In_0.7Ga_0.3As tunneling field-effect-transistors (TFETs) using the p⁺ (6 nm)/undoped (6 nm) tunneling junction with 5-nm HfO₂ gate oxides have been demonstrated with an on-current of 50 μA/μm and a minimum subthreshold swing (SS) of 86 mV/dec. The impacts of tunneling junction structures on TFETs´ performance have been investigated. It has been found that In_0.7Ga_0.3As TFETs with the p⁺ (4 nm)/undoped (8 nm) tunneling junction provide ~ 80% higher on -currents than In_0.7Ga_0.3As TFETs with the p⁺ (6 nm)/undoped (6 nm) junction, and In_0.7Ga_0.3As TFETs exhibit much higher on-currents than In_0.53Ga_0.47As TFETs. Different atomic-layer-deposited gate oxides have been used, and Al₂O₃/HfO₂ bilayer gate oxides effectively improve the SS compared with HfO₂ single gate oxide. The effects of equivalent oxide thickness scaling and operating temperatures on the on-current, the SS, and the gate-bias-dependent Esaki diode behavior have been also investigated.