Silicon nanomembrane-based near infrared phototransistor with positive and negative photodetections.

Surface plasmon polariton induces hot carrier injection that enables near infrared photodetection in Si nanomembranes and is of great significance for Si photonics integrated circuits. In this study, near infrared photodiode and phototransistor based on Si nanomembranes are designed and demonstrated, where the channel carrier concentration can be tuned through a gate modulation to implement both positive and negative photodetections. Through patterning a nanogroove array, Si nanomembrane-based photodetector exhibits high performance in near infrared range with an Ion/Ioff ratio of 102, and a responsivity of 7 mA W-1, under 1550 nm laser irradiation. Moreover, the photodetection ability, determined by Ioff/Ion can be further enhanced to ∼6 × 102 when the photodetector is modulated to work at the negative photodetection mode. Our study may provide a practical approach with fundamental guidelines and designs for fabricating high-performance Si-based infrared photodetection, which promotes the development of Si photonics.