Abstract
In this work, flexible solar blind Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ultraviolet photodetectors with high responsivity and photo-to-dark current ratio are demonstrated. The Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> films are obtained by the RF magnetron sputtering method on flexible polyimide (PI) substrates and the results demonstrate that all the films grown under various temperatures are amorphous. When the incident light wavelength is less than 254 nm, the incident light is effectively absorbed by the Ga <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> film. By controlling the growth temperature of the material, the responsivity and photo-to-dark current ratio of the corresponding metal-semiconductor-metal photodetectors are significantly improved. At growth temperature of 200 °C, the current under 254 nm illumination obtains 396 nA at voltage of 20 V (corresponding responsivity is 52.6 A/W), the photo-to-dark current ratio is more than 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> , and the external quantum efficiency reaches 2.6 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> %, which is among the best reported Ga2O3 ultraviolet photodetectors including the devices on the rigid substrates. After the bending and fatigue tests, the flexible detectors have negligible performance degradation, showing excellent mechanical and electrical stability.
Highlights
In today’s fast-developing information age, optoelectronic technology has become a frontier discipline in the information industry
The films grown on the rigid substrates at 200 °C are amorphous as Fig. S1 shows, indicating that under such a low growth temperature range (50 °C to 200 °C) the crystal Ga2O3 cannot be formed no matter what the substrate is
It can be observed that the Ga2O3 film on the PI substrate shows a cutoff absorption wavelength between 500 nm and 600 nm, and it is obviously not corresponding to the Ga2O3 material with a bandgap near 5.0 eV
Summary
In today’s fast-developing information age, optoelectronic technology has become a frontier discipline in the information industry. A wide variety of optoelectronic devices, such as lasers [1], light-emitting diodes [2], photodetectors [3], [30] and solar cells [4], have penetrated into all aspects of human life and work They play an important role in the fields of space exploration [5] and national defense security. As a wide bandgap oxide semiconductor material, Ga2O3 has a quasi-direct gap of up to 4.8 eV, and its photoresponse peak falls in the solar-blind band. It does not require energy band regulation, and its absorption coefficient near the absorption edge is as high as 105 cm−1. The flexible photodetectors show excellent mechanical and electrical stability
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