Remarkably High-Performance Nanosheet GeSn Thin-Film Transistor

Abstract

High-performance p-type thin-film transistors (pTFTs) are crucial for realizing low-power display-on-panel and monolithic three-dimensional integrated circuits. Unfortunately, it is difficult to achieve a high hole mobility of greater than 10 cm2/V·s, even for SnO TFTs with a unique single-hole band and a small hole effective mass. In this paper, we demonstrate a high-performance GeSn pTFT with a high field-effect hole mobility (μFE), of 41.8 cm2/V·s; a sharp turn-on subthreshold slope (SS), of 311 mV/dec, for low-voltage operation; and a large on-current/off-current (ION/IOFF) value, of 8.9 × 106. This remarkably high ION/IOFF is achieved using an ultra-thin nanosheet GeSn, with a thickness of only 7 nm. Although an even higher hole mobility (103.8 cm2/V·s) was obtained with a thicker GeSn channel, the IOFF increased rapidly and the poor ION/IOFF (75) was unsuitable for transistor applications. The high mobility is due to the small hole effective mass of GeSn, which is supported by first-principles electronic structure calculations.

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

“…Similar results of higher µ FE but poorer I OFF and I ON / I OFF in thicker channel are also found in highly conductive GeSn p‐type TFT. [ 76 ]…”

“…Similar results of higher µ FE but poorer I OFF and I ON /I OFF in thicker channel are also found in highly conductive GeSn p-type TFT. [76] Table 2 shows the comparison of electrical characteristic of SnON with different channel thickness. The transistor's µ FE increases with increasing channel thickness, from 277 cm 2 V −1 s −1 (5 nm of SnON) to 299 cm 2 V −1 s −1 (7 nm of SnON).…”

37.1: Invited Paper: Nanosheet High Mobility SnO2‐SnO Complementary TFTs for System‐on‐Display and Monolithic Three‐Dimensional Integrated Circuit

“…This is also the obstacle for p type TFT to achieve high mobility. Further improvement is possible by using our latest research-the even higher hole mobility GeSn pTFT [12], which has high potential to fulfill high performance CTFTs.…”

Polycrystalline GeSn Films Grown by Hot Wire Chemical Vapor Deposition on SiO2/Si(001) Substrates

“…Excellent prospects for the use of polycrystalline GeSn films to create TFTs were reported in 2022. [ 5 ] The authors demonstrate a high‐performance GeSn p‐TFT with a high hole mobility of 41.8 cm 2 V −1 × s −1 , having a switching level ( I ON / I OFF ) of up to 8.9 × 10 6 . To obtain polycrystalline GeSn films with high carrier mobility, they are formed on dielectric substrates by solid‐phase crystallization of amorphous GeSn films using thermal [ 6 ] and laser annealing [ 7,8 ] and metal‐induced crystallization.…”