Origin of positive Vth shift and mobility effects in amorphous GaInZnO thin films

Sung Heo, Dongwha Lee, Yong Koo Kyoung, Young Nam Kwon, Ki Hong Kim, Jae Gwan Chung, Jae Cheol Lee, Gyeong Su Park, Jong Soo Oh, Dahlang Tahir, Hee Jae Kang, Hoon Young Cho

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

We investigated the relationship between band alignments and threshold voltage shifts of GaInZnO (GIZO) thin films grown on SiO2/p++-Si by the RF sputtering method via utilizing X-ray photoelectron spectroscopy and reflection electron energy loss spectroscopy. The band gap energies of the GIZO thin films are increased from 3.03 eV to 3.43 eV with the increase in their Gallium (Ga)/Indium (In) ratios of 0.83, 1.05, and 1.34. The barrier height of GIZO/Mo is also increased by increasing in the Ga/In ratio, and then the threshold voltages positively shift. From the result of DLTS, it is found that the D defect is located at 0.56 eV below the conduction band, and its defect density shows the increasing tendency by the increase in the ratio of Ga/In (i.e. the decrease in In content). From the transfer curves of the GIZO thin films, the mobility shows the decreasing tendency by the increase in the ratio of Ga/In. As a result, it is suggested that the increase in the density of D defect density in the GIZO thin film plays a dominant role in the decrease in its mobility.

Original languageEnglish
Pages (from-to)456-460
Number of pages5
JournalThin Solid Films
Volume616
DOIs
StatePublished - 1 Oct 2016

Keywords

  • Band alignment
  • Band bap
  • Ga-In-Zn-O
  • REELS
  • Vth shift
  • XPS

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