摘要
High sensitivity,high solar rejection ratio,and fast response are essential characteristics for most practical applications of solar-blind ultraviolet(UV)detectors.These features,however,usually require a complex device structure,complicated process,and high operating voltage.Herein,a simply structured n-Al Ga N/Al N phototransistor with a self-depleted full channel is reported.The self-depletion of the highly conductive n-Al Ga N channel is achieved by exploiting the strong polarization-induced electric field therein to act as a virtual photogate.The resulting two-terminal detectors with interdigital Ohmic electrodes exhibit an ultrahigh gain of 1.3×10^(5),an ultrafast response speed with rise/decay times of 537.5 ps/3.1μs,and an ultrahigh Johnson and shot noise(flicker noise)limited specific detectivity of 1.5×10^(18)(4.7×10^(16))Jones at 20-V bias.Also,a very low dark current of the order of~p A and a photo-to-dark current ratio of above 10^(8)are obtained,due to the complete depletion of the n-Al_(0.5)Ga_(0.5)N channel layer and the high optical gain.The proposed planar phototransistor combines fabrication simplicity and performance advantages,and thus is promising in a variety of UV detection applications.
基金
Key Realm R&D Program of Guangdong Province(2019B010132004,2020B010172001)
Key Realm R&D Program of Guangzhou(202103030002)。
