Ultrasensitive self-filtering visible-light phototransistor using InGaN/GaN single-carrier superlattices and polarization depletion

Visible-light bandpass field effect phototransistors (FEPTs) with ultrahigh sensitivity and strong wavelength selectivity are fabricated using InGaN/GaN single-carrier superlattices (SCSLs) and polarization-induced depletion. The pure polarization electric field generated at the heterointerface is utilized to deplete the SCSLs, achieving the low dark current leakage with a float photogate. Meanwhile, the SCSLs with well-designed barrier thickness are introduced as the absorber and the channel, which can effectively separate the photoexcited carriers and suppress carrier recombination, thereby contributing to the ultrahigh photocurrent gain. With back illumination, the device achieves an ultrahigh shot noise limited detectivity of 1.8 × 10 18 Jones and an extremely strong narrowband selectivity with spectral rejection ratios above 10 8 . Moreover, the FEPT demonstrates pretty good long-term stability and adaptability to complex illumination conditions. Compared with traditional Si photodetectors, these superior performance metrics provide a practical and convenient option for various applications requiring weak light detection and color distinguishing.