AlGaN/GaN Double-Channel Ultraviolet Photodetector With Polarization-Enhanced Photoresponsivity

In this work, an ultraviolet photodetector (UV PD) based on an AlGaN/GaN double-channel (DC) heterostructure is demonstrated. The carriers in both channels are partially depleted by a recessed trench to suppress the dark current. A high photoresponsivity of 2.6×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> A/W is realized in the DC PD under 365-nm light illumination even with a low intensity of 3.8 μW/cm<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, which is ~30 times higher than that of a single-channel (SC) counterpart. Moreover, a high specific detectivity of 3.4×10<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> cm·Hz½/W and a relatively short decay time constant of ~2.3 ms have been achieved in the DC PD. The high photoresponsivity is possibly correlated with the spatial separation of the photogenerated carriers under the internal polarization field at the dual AlGaN/GaN heterointerface, as well as the photo-induced leakage current across the recessed trench. The GaN-based DC PD and the mechanism analysis in this work can provide valuable insights towards enhanced photoresponsivity especially for weak-light detection.