Switching Enhancement via a Back-Channel Phase-Controlling Layer for p-Type Copper Oxide Thin-Film Transistors

Won Kyung Min, Sung Pyo Park, Hee Jun Kim, Jin Hyeok Lee, Kyungho Park, Dongwoo Kim, Ki Woo Kim, Hyun Jae Kim

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22 Citations (Scopus)


P-type copper oxide (CuxO) thin-film transistors (TFTs) with enhanced switching characteristics were fabricated by introducing a sputter-processed capping layer capable of controlling the back-channel phase (labeled as phase-controlling layer, PCL). By optimizing the processing conditions (the deposition power and postdeposition annealing parameters), the switching characteristics of the TFTs achieved a subthreshold swing of 0.11 V dec-1, an on/off current ratio (Ion/Ioff) of 2.81 × 108, and a field-effect mobility (μFET) of 0.75 cm2 V-1 s-1, a considerable enhancement in performance compared to that of CuxO TFTs without the PCL. Through optical/electrical analyses and technology computer-aided design simulations, we determined that the performance improvements were because of the CuxO back-channel phase reconstruction through PCL deposition and subsequent annealing. The two factors that occurred during the process, sputtering damage and heat treatment, played key roles in creating the phase reconstruction by inducing a local phase transition that sharply reduced the off-current via controlling back-channel hole conduction. As a sample application, we fabricated a complementary metal oxide semiconductor inverter based on our optimized CuxO TFT and an InGaZnO TFT that demonstrated a large inverter voltage gain of >14. The proposed approach opens up advancements in low-power circuit design by expanding the utilization range of oxide TFTs.

Original languageEnglish
Pages (from-to)24929-24939
Number of pages11
JournalACS Applied Materials and Interfaces
Issue number22
Publication statusPublished - 2020 Jun 3

Bibliographical note

Funding Information:
This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea Government (MSIT) (no. 2017R1A2B3008719).

Publisher Copyright:
© 2020 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • Materials Science(all)


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