High-gain high-sensitivity AlGaN/GaN ultraviolet photodetector with effective mechanism for photocurrent collection

A high-performance AlGaN/GaN-based ultraviolet photodetector with a field-enhanced mechanism for photocurrent collection is designed and fabricated in this work. In addition to the inherent polarization field, two additional sets of collection fields are formed from a 2DEG layer to a ITO thin film and from the 2DEG layer to a cathode electrode sinker. The effectiveness in the collection of photogenerated carriers is remarkably enhanced, which leads to a photocurrent of 6.6 mA/mm under the illumination of 365 nm-centered ultraviolet light at an intensity of 1.8 mW/cm(2). With an in-built shallow isolation trench, the dark current is suppressed below 40 pA/mm under a device bias of 5.0 V. A photo-to-dark current ratio as high as 1.7 x 10(8), a record high photo-responsivity over 4.3 x 10(6 )A/W, and a high gain of 1.46 x 10(7) under 365-nm light are demonstrated by the fabricated prototype, showing great competitiveness in state-of-the-art AlGaN/GaN-based ultra-violet photodetectors. Published under an exclusive license by AIP Publishing.