Modulation of the Al/Cu2O Schottky Barrier Height for p-Type Oxide TFTs Using a Polyethylenimine Interlayer

Hee Jun Kim, Sung Pyo Park, Won Kyung Min, Dongwoo Kim, Kyungho Park, Hyun Jae Kim

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4 Citations (Scopus)


We introduced an organic interlayer into the Schottky contact interface to control the contact property. After inserting an 11-nm-thick polyethylenimine (PEI) interlayer between the aluminum (Al) source/drain electrode and the cuprous oxide (Cu2O) channel layer, the Cu2O thin-film transistors (TFTs) exhibited improved electrical characteristics compared with Cu2O TFTs without a PEI interlayer; the field-effect mobility improved from 0.02 to 0.12 cm2/V s, the subthreshold swing decreased from 14.82 to 7.34 V/dec, and the on/off current ratio increased from 2.43 × 102 to 1.47 × 103, respectively. Careful investigation of the contact interface between the source/drain electrode and the channel layer established that the performance improvements were caused by the formation of electric dipoles in the PEI interlayer. These electric dipoles reduced the Schottky barrier height by neutralizing the charges at the metal/oxide semiconductor interface, and the holes passed the reduced Schottky barrier by means of tunneling or thermionic injection. In this way, p-type oxide TFTs, which generally need a noble metal having a high work function as an electrode, were demonstrated with a low-work-function metal. As a basic application for logic circuits, a complementary inverter based on n-type indium-gallium-zinc oxide and p-type Cu2O TFTs was fabricated using only Al source/drain electrodes. This research achieved advances in low-cost circuit design by broadening the electrode metals available for the manufacture of p-type oxide semiconductor-based electronics.

Original languageEnglish
Pages (from-to)31077-31085
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number26
Publication statusPublished - 2021 Jul 7

Bibliographical note

Funding Information:
This work was supported by LG Display and the Nano-Material Technology Development Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT under grant 2018M3A7B4071521.

Publisher Copyright:
© 2021 American Chemical Society. All rights reserved.

All Science Journal Classification (ASJC) codes

  • Materials Science(all)


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