Electrical Properties of Double-Gate Field-Effect Transistor Based on MA₂N₄ (M = Ti, Zr, and Hf; A = Si, Ge, and Sn) Monolayers

The electrical characteristics of a double-gate field-effect transistor (DGFET) based on the MA2N4 family of 2-D monolayers as channel materials are studied. The materials’ key electronic parameters, including effective mass, bandgap, and work function are investigated using density functional theory. Assessment of band structures suggests that MSi2N4 and TiGe2N4 are indirect semiconductors, whereas other compounds demonstrate direct bandgap. The projected density of state is obtained to explore the contribution of M and Z elements to both conduction and valence bands. The quantum transport characteristics of the double gate FET with MA2N4 monolayers have been studied using non-equilibrium Green function (NEGF) formalism. The current–voltage characteristics are obtained, and several essential device parameters of the FET including ON-current, OFF-current, ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio, and sub-threshold swing (SS) are extracted. Few monolayers of this family demonstrated better short channel device characteristics when used as channel materials, including ${I}_{ \mathrm{\scriptscriptstyle ON}}/{I}_{ \mathrm{\scriptscriptstyle OFF}}$ ratio $\ge 10^{{8}}$ and a SS of about 60 mV/dec for the channel length down to 5 nm.