Outstanding High Field‐Effect Mobility of 299 cm² V⁻¹ s⁻¹ by Nitrogen‐Doped SnO₂ Nanosheet Thin‐Film Transistor

Abstract Record high field‐effect mobility (µ_FE) thin film transistors (TFTs) based on 5 and 7 nm thickness SnON channel layer is reported. The SnON TFT device with 7.6% nitrogen content achieves a record high µ_FE of 299 cm² V⁻¹ s⁻¹ at 7 nm thickness and 277 cm² V⁻¹ s⁻¹ at 5 nm thickness, compared to SnO₂ with µ_FE of 211 cm² V⁻¹ s⁻¹. At the same 5 nm quasi‐2D channel thickness, this µ_FE of nanocrystalline SnON transistor is comparable to single crystalline Si and InGaAs metal oxide semiconductor field‐effect transistor (MOSFET) and also higher than the phonon‐scattering‐limited 2D MoS₂ FET. From the principle of quantum‐mechanical calculation, the high µ_FE of nanosheet SnON TFT is due to lower effective mass of electrons, 0.29 m₀ in the conduction band in contrast to 0.41 m₀ of SnO₂. SnON can reduce the defect trap densities by introducing non‐oxide anions where the valence band can be controlled to remove or passivate the oxygen vacancy levels by substitutional alloying with nitrogen anions to circumvent instability, increase on‐current (I_ON) and improve the µ_FE. It is highly expected that the high performance quasi‐2D nanosheet SnON TFTs will be utilized in embedded DRAM and monolithic 3D integrated circuits (ICs).