Electric-Dipole Gated Two Terminal Phototransistor for Charge-Coupled Device

The demand for charge-coupled device (CCD) imagers has surged exponentially during the last decade owing to their exceptionally high quality and low noise imaging. However, they are still confronting the performance constraints of high operation power, low speed, and limited charge integration. Here, the electric-dipole gated phototransistor operation without external gate bias is reported by using high-k HfO2 dielectric material. The electrostatic coupling of photogenerated charges from the Si with the graphene channel through a 10 nm HfO2 layer is demonstrated. The device exhibits remarkable performance in the broadband spectrum (266-1342 nm) at low drain bias voltage. The high values of responsivity, external quantum efficiency, and detectivity of 3.7 x 10(3) A W-1, 0.72 x 10(4), and 6.20 x 10(13) cmHz(1/2) W-1, respectively, for 800 nm wavelength and 3.3 x 10(3) A W-1, 1.31 x 10(4), and 5.61 x 10(13) cmHz(1/2) W-1, respectively, for 400 nm wavelength without gate are achieved. This discovery may potentially eliminate the requirement for gate terminals from commercial CCD devices. The power efficient features of this gateless image sensor can be fabricated at the industrial scale for the future machine vision market.