Origin of the responsivity characteristics of the MgyZn1-yO metal-semiconductor-metal photodetectors with different electrode spacings

• MgyZn1-yO MSM structured PDs fabricated with different films and electrode spacings.
• The Mg0.20Zn0.80O PDs have larger responsivity than the Mg0.42Zn0.52O ones.
• The responsivity of MgyZn1-yO PDs increases with the electrode spacings decreasing.
• The responsivity performances were interpreted by the metal-semiconductor junction.

We fabricate MgyZn1-yO metal-semiconductor-metal ultraviolet photodetectors by integrating Au electrodes (with different electrode spacings) onto a semiconductor film (Mg0.20Zn0.80O or Mg0.42Zn0.58O), prepared by the radio frequency magnetron sputtering deposition method. As expected, the Mg0.20Zn0.80O photodetectors have a larger responsivity than the Mg0.42Zn0.58O ones when the electrode spacing and bias voltage are constant. More interestingly, the responsivity of all the MgyZn1-yO photodetectors increase with decreasing electrode spacing for the same bias. These results are well-understood in terms of the role played by the metal-semiconductor junction.

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