Influence of oxygen flow during sputtering process on the electrical properties of Ga-doped InZnSnO thin film transistor

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Abstract
This work presents the electrical properties of the amorphous gallium doped indium zinc tin oxide (Ga-IZTO) thin film transistors (TFTs), as a function of O2 flow rate (Ar / O2), during the sputtering process of channel layer. As the O2 flow rate increased from 30 : 0 to 30 : 7, the saturation mobility (μSAT) monotonically degraded from 31.5 cm2V-1s-1 to 12.0 cm2V-1s-1, the threshold voltage (VTH) shifted from 0.8 V to 6.8 V, The VTH shift (ΔVTH) induced by the negative bias stress (NBS) improved from -7.0 V to -2.8 V. XRD analysis indicated that all the films are amorphous which is independent of O2 flow rate. Transmittance spectra reflected that the average transmittance of thin film is sensitive to O2 flow rate and decreases as the O2 flow rate increases. XPS analysis revealed that the density of oxygen vacancy is reduced and the oxygen lattices are enhanced, as the O2 flow rate increases. The Hall effect measurements indicated the carrier concentration (n) was reduced with increasing O2 flow rate. These results show that the electrical properties of Ga-IZTO TFTs can be easily tuned by the O2 flow rate during sputtering process. The related mechanism for the variations of electrical properties of Ga-IZTO TFT have been discussed in detail.
Funding Information
  • Fundamental Research Funds for the Central Universities (2020YJS188)
  • National Natural Science Foundation of China (51772019)