Highly sensitive visible and near-infrared photo-FET based on PbS quantum dots embedded in the gate insulator

Abstract

New photo Thin-Film Transistor able to detect light in red and near-infrared wavelength range with high detectivity and high speed, is developed. Detectivity of 1013 Jones at 850 nm is obtained. The rise time and the fall time of the answer to pulsed light are 46 ms and 10 ms respectively. Responsivity value is 1700 A/W at 760 nm and 13 A/W at 1.3μm. The photo-transistor is based on the light absorption by PbS quantum-dots that are embedded in an epoxy based (SU8 photoresist) thin-film matrix. This thin-film acts as the gate insulator of the transistor and it replaces the usual silicon dioxide gate insulator. The TFT's fabrication is made through a usual top-gate LTPS-TFT process only replacing the top-gate insulator by the mixed QDs-SU8 film. Present TFTs can be easily integrated in any Large-Area electronics process.