Boosted UV Photodetection Performance in Chemically Etched Amorphous Ga₂O₃ Thin‐Film Transistors

Abstract

Abstract A three‐terminal thin‐film transistor (TFT) architecture is essential for photodetectors to reach a good balance between high responsivity and fast response speed. Bottom‐gate amorphous Ga 2 O 3 (a‐Ga 2 O 3 ) TFTs are fabricated to boost their UV photodetection properties. During the device fabrication process, a simple chemical‐etching solution with the advantages of easy operation, low cost, and compatibility with traditional lithography process, is developed to selectively etch a‐Ga 2 O 3 films. The a‐Ga 2 O 3 channel etched device on Si manifests an effective suppression of the commonly observed gate leakage current. Meanwhile, a patterned a‐Ga 2 O 3 TFT on quartz shows an excellent n‐type TFT performance with an on/off ratio as high as ≈10 7 . It is further applied as a phototransistor, to diminish the persistent photoconductivity (PPC) effect while keeping a high responsivity ( R ) as well. Under the 254 nm UV illumination, the a‐Ga 2 O 3 phototransistor demonstrates a high light‐to‐dark ratio of 5 × 10 7 , a high responsivity of 5.67 × 10 3 A W −1 , and a high detectivity of 1.87 × 10 15 Jones. Remarkably, the PPC phenomenon in a‐Ga 2 O 3 UV phototransistors is effectively suppressed by applying a positive gate pulse, which greatly shortens the decay time to 5 ms and offers a‐Ga 2 O 3 possible inroads into imaging applications.