Remarkably High Effective Mobility of 301 cm2/V·s in 3 nm Ultra-Thin-Body SnO2 Transistor by UV Annealing

TL;DR

A 3 nm ultra-thin SnO2 transistor achieves high mobility and performance through UV annealing, outperforming other 2D materials and silicon.

Contribution

Demonstrates a 3 nm SnO2 transistor with a record effective mobility of 301 cm2/V·s using UV annealing.

Findings

UV annealing significantly improves effective and field-effect mobility in 3 nm SnO2 transistors.

The subthreshold swing is sharpened to 201 mV/decade, enhancing low-power performance.

SnO2's wide bandgap allows operation at higher voltages, enabling potential ternary logic applications.

Abstract

At an ultra-thin 3 nm SnO2 channel thickness, a record-high effective mobility (µeff) of 301 cm2/V·s, field-effect mobility (µFE) of 304 cm2/V·s, and a sharp subthreshold swing (SS) of 201 mV/decade are achieved at a high carrier density (Ne) of 5 × 1012 cm−2. These excellent transport properties are attributed to ultraviolet (UV) light annealing. The resulting µeff is significantly higher than that of Molybdenum Disulfide (MoS2) and Tungsten Diselenide (WSe2), and is more than twice that of single-crystalline Si channel transistors at the same quasi-two-dimensional (2D) thickness of 3 nm (equivalent to five monolayers of MoS2). UV annealing not only enhances µeff and µFE but also sharpens the SS, which is crucial for low-power operation. This improved SS is attributed to reduced scattering from charged interface traps, as supported by µeff-Ne analysis, thereby increasing the transistor’s mobility. The realization of such high-mobility devices at a quasi-2D thickness of only 3 nm is of particular importance for the further downscaling of ultra-thin-body transistors for high-speed computing and monolithic three-dimensional (M3D) integration. Furthermore, the wide bandgap of SnO2 (3.7 eV) enables operation at relatively high voltages, paving the way for pioneering ternary logic applications.

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