High Field-Effect Mobility Two-Channel InGaZnO Thin-Film Transistors for Low-Voltage Operation

Kwang Ro Yun, Hwa Seub Lee, Jong Ho Kim, Tae Ju Lee, Jin Seong Park, Tae Yeon Seong

Research output: Contribution to journalArticlepeer-review


In this study, two-channel thin-film transistors (TC TFTs) using sputtered-deposited amorphous indium-gallium-zinc oxide (a-IGZO) as a channel layer and atomic-layer-deposition Al&#x2082;O&#x2083; as gate insulator (GI) are proposed for wearable and portable device application. Symmetric-TC (S-TC) TFT structure consisted of conventional bottom gate (BG) TFT stacked on top of top gate (TG) TFT. Asymmetric-TC (A-TC) TFT contained BG TFT with tandem structure on the TG TFT. It was shown that the TC TFTs exhibited excellent performance such as high field-effect mobility ( <formula> <tex>$&#x03BC;_{FE}$</tex> </formula> ) and on/off current ratio ( <formula> <tex>$I_{t{on/off}}$</tex> </formula> ) at low voltages (&lt;2 V). For instance, the S-TC TFTs gave <formula> <tex>$&#x03BC; _{FE}$</tex> </formula> of 19.67 cm&#x00B2;/Vs and <formula> <tex>$I_{t{on/off}}$</tex> </formula> of 5.48 x 10&#x2078;. Furthermore, the A-TC TFTs with tandem structure yielded <formula> <tex>$&#x03BC; _{FE}$</tex> </formula> of 30.15 cm&#x00B2;/Vs, a small threshold voltage of -1.25, a low subthreshold swing of 89 mV/decade, and a high <formula> <tex>$I_{t{on/off}}$</tex> </formula> of 1.70 x 10&#x2079;. It was found that the TC TFTs demonstrated better electrical performance than the sum of individual TG and BG TFTs. Under bias stress tests, the TC TFTs experience less <formula> <tex>$V_{th}$</tex> </formula> shift ( <formula> <tex>$&#x0394; V_{th}$</tex> </formula> ) than the TG and BG TFTs.

Original languageEnglish
JournalIEEE Transactions on Electron Devices
Publication statusAccepted/In press - 2021


  • Amorphous indium-gallium-zinc oxide (a-IGZO)
  • field-effect mobility
  • Iron
  • Logic gates
  • Low voltage
  • low-voltage operation
  • NIST
  • Stress
  • Thermal stability
  • Thin film transistors
  • two-channel thin-film transistor (TC TFTs).

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Electrical and Electronic Engineering


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