Discussion on a Source Follower Type Image Sensor Driven from Back Electrodes

Abstract

An image sensor is proposed which is driven from back of image sensing area and which detects the channel potential modulated by the stored signal charge. The characteristics of the sensor with 1, 000×1, 000 cell/cm² were simulated by a numerical analysis which solves simultaneous continuity equations for the potential, the electron and hole currents. In this analysis, a driving method is adopted which suppresses blooming during the charge storage time but allows it only during the very short readout time. The analysis indicated that the charge handling capability reaches 1.53×10⁵ hole/cell and that the conversion factor is 3.7 μV/hole. The proposed sensor promises to have high photo-sensitivity and wide dynamic range.