Electrode‐Dependent Electrical Properties of Detection‐Band Tunable Ultraviolet Photodetectors Based on Ga 2 O 3 /GaN Heterostructures

The polycrystal Ga 2 O 3 on GaN was realized by high‐temperature oxidization of the GaN films with oxidation time 1 and 10 h, and the metal‐semiconductor‐metal photodetectors based on the Ga 2 O 3 /GaN heterostructure were fabricated by using Ti and Au metal electrodes. A comparative study of different electrodes and oxidation time on the performance of ultraviolet photodetector is performed. Among the devices prepared by 1 h oxidation, it is found that the device fabricated with Au electrode shows a lower dark‐current and higher photocurrent than the one with Ti electrode. This is mainly due to the higher Schottky barrier height of sample with Au electrode. As for the device that experienced 10 h oxidation with Au electrode, the solar‐blind responsivity with the full width at half maxima of 12 nm was obtained, which can be attributed to thicker Ga 2 O 3 film. The devices exhibit excellent performance, including low dark‐current and satisfactory responsivity, even under ultra‐weak signal. The authors attribute these excellent properties to the Ga 2 O 3 film, as it has a large grain size and a porous structure. The results provide a simple method that is low‐cost and high‐output with large‐area production of high‐performance ultraviolet photodetectors.