Room-Temperature-Synthesized High-Mobility Transparent Amorphous CdO-Ga2O3 Alloys with Widely Tunable Electronic Bands

Chao Ping Liu, Chun Yuen Ho, Roberto dos Reis, Yishu Foo, Peng Fei Guo, Juan Antonio Zapien, Wladek Walukiewicz, Kin Man Yu*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


In this work, we have synthesized Cd1-xGaxO1+δ alloy thin films at room temperature over the entire composition range by radio frequency magnetron sputtering. We found that alloy films with high Ga contents of x > 0.3 are amorphous. Amorphous Cd1-xGaxO1+δ alloys in the composition range of 0.3 < x < 0.5 exhibit a high electron mobility of 10-20 cm2 V-1 s-1 with a resistivity in the range of 10-2 to high 10-4 ω cm range. The resistivity of the amorphous alloys can also be controlled over 5 orders of magnitude from 7 × 10-4 to 77 ω cm by controlling the oxygen stoichiometry. Over the entire composition range, these crystalline and amorphous alloys have a large tunable intrinsic band gap range of 2.2-4.8 eV as well as a conduction band minimum range of 5.8-4.5 eV below the vacuum level. Our results suggest that amorphous Cd1-xGaxO1+δ alloy films with 0.3 < x < 0.4 have favorable optoelectronic properties as transparent conductors on flexible and/or organic substrates, whereas the band edges and electrical conductivity of films with 0.3 < x < 0.7 can be manipulated for transparent thin-film transistors as well as electron transport layers.

Original languageEnglish (US)
Pages (from-to)7239-7247
Number of pages9
JournalACS Applied Materials and Interfaces
Issue number8
StatePublished - Feb 28 2018


  • amorphous transparent conducting oxides
  • flexible electronics
  • oxide semiconductors
  • transparent conductors
  • transparent electronics

ASJC Scopus subject areas

  • Materials Science(all)


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