The Fabrication And Study Of ZnO-Based Double-color Photodetectors

ZnO thin film,a kind of direct wide-bandgap semiconductor material with adjustable band gap?band gap width at room temperature is about 3.37 eV?,can be synthesized into MgZnO ternary alloy by doping Mg element.The band gap width of Mg_xZn_1-xO film is adjustable in the range of 3.37 eV to 7.80 eV,which can broaden the detector's detection wavelength range.The double-colors photodetector with excellent performance can be fabricated by using different Mg composition and different structure of the semiconductor film.This paper mainly describes the growth of ZnO-based semiconductor films,the fabricated of double-color photodetectors,and the improvement of the film quality to enhance the performance of double-color device.The main research work is as follows:?1?Considering the two-layer film structure,the crystal quality of the semiconductor films deposited at different sputtering powers was fabricated.When the sputtering power was 160 W,it was found by SEM spectroscopy that the growth particle size of the film was relatively uniform,and the diffraction peak of the XRD pattern was fairly high.A series of double-color detector devices was prepared based on such films.The peak responsivity of Mg_0.38Zn_0.62O and ZnO deposited at the power of 160W reached 0.45 A/W and 0.30 A/W,which was increased by 450%and 225%contrasted with the power of 140 W and 180 W,respectively.By comparing the two different film structures of Mg0.20Zn0.80O/ZnO and ZnO/Mg_0.20Zn_0.80O,it can be seen that the influence of the electric field intensity generated by the metal electrode on the semiconductor film changed with the distance.Furthermore,the performance of the device is effectively regulated by adjusting the position of the semiconductor film.?2?Design the sandwich structure to construct a double-color photodetector.Based on the advantages of the double Schottky junction of the sandwich structure itself,the semiconductor film and the metal electrode were grown under the different conditions of substrate tray temperature of room temperature,523 K,673 K and 723 K,respectively.It was found that the film quality was getting better with increasing temperature,however,the metal electrode was damaged to some extent.Considering the influence of temperature on the two aspects,the device obtained at 673 K has the highest photoelectric performance,and the peak responsivity values of Mg0.20Zn0.80O and ZnO are about 1.30 A/W and 0.30A/W,respectively.By comparison with the two-layer film structure detectors,it is known that under the effect of the double Schottky junction,the sandwich structure detector possess a stronger ability to collect carriers,and both of the two responsivity peaks reached1.50 A/W,which improved the photoelectric performance of the device effectively.?3?Different from the traditional complex double-color photodetectors,the detector based on the mixed-phase semiconductor thin film could realize double-color detection while simplifying the device structure.By preparing a mixed-phase Mg_0.40Zn_0.60O film of high Mg composition,the device responded to light in two different wavelength bands.Further changing the electrode width of the detector based on mixed-phase thin film to broaden the width of the Schottky junction depletion layer,thereby effectively improving the photoelectric properties of the device.At the same bias voltage,the responsivity peak elevated from 1.60 A/W to 3.10 A/W as the electrode width increased from 3?m to 8?m.