Dual broadband photodetector based on interband and intersubband transitions in InAs quantum dots embedded in graded InGaAs quantum wells

Abstract

Two broadband photoresponse from InAs quantum dots embedded in graded InGaAs quantum well photodetectors were observed in the spectral regions of 4–12μm (midinfrared band) and 0.5–1.0μm (near-infrared-visible band). The midinfrared band is attributed to the intersubband transitions within the quantum dots and was observed at temperatures less than 80K. The near-infrared-visible band is attributed to interband transitions and is observed in the temperature range of 77–300K. The room temperature detectivity of the near-infrared-visible band is estimated to be on the order of ∼3.0×108cmHz∕W with a bias voltage less than 1.0V.