Multilayer MoS₂ Back‐Gate Transistors with ZrO₂ Dielectric Layer Optimization for Low‐Power Electronics

Abstract

Herein, high‐performance back‐gate molybdenum disulfide (MoS2) field‐effect transistors (FETs) with high‐quality sub‐20 nm high‐k dielectric layers are developed for high‐performance and lower‐power consumption applications. The 20 nm ultrathin ZrO2 dielectric layers are deposited by thermal atomic layer deposition (ALD) method, where the growth temperature is varied and it shows a significant impact on the electrical characteristics of the deposited ZrO2 materials. A polydimethylsiloxane (PDMS) transfer process is used to transfer multilayer MoS2 flakes onto a 20 nm ZrO2/p–Si substrate with an optimized dielectric growth temperature without any subsequent processing, resulting in back‐gate MoS2 FET device architecture. These transistors demonstrate excellent electrical characteristics with on–off current ratio up to 1.8 × 107, subthreshold swing as low as 70 mV decade−1 and field‐effect mobility as high as 3.9 cm2 V−1 s−1. Furthermore, an enhancement‐mode device operation and a high complementary metal–oxide–semiconductor (CMOS) ION/IOFF ratio of 107 are achieved. The excellent electrical performance is attributed to the low interface state traps and high‐quality ZrO2 dielectric layer, indicating the great potential of our multilayer MoS2 FETs technology for low‐power applications.

A critical review of fabrication challenges and reliability issues in top/bottom gated MoS2field-effect transistors

“…Typically, the thicknesses of 90 and 270 nm SiO 2 thickness results in optimum colour contrast for the detection of mono-layer and few layer MoS 2 flakes [43,44]. It is to be noted that MoS 2 can be successfully exfoliated/transferred onto different high-k dielectric oxide layers like Al 2 O 3 [45], HfO 2 [46], ZrO 2 [47] that can potentially result in increased back-gating efficiency. Velicky et al, recently demonstrated successful mechanical exfoliation of monolayer MoS 2 on metallic substrates including Au, Pt, Pd and Ag.…”