Comparative Performance Evaluation of Conventional and Folded Detector Structures: Application to Perovskite X-ray Detectors

Abstract

The imaging performance of a semiconductor radiation imaging detector critically depends on its photoconductor layer thickness. The conventional detector structure (i.e., a photoconductor layer is sandwiched between two parallel electrodes) needs a strict design criterion on photoconductor thickness as compared to folded detector structure for optimizing the detective quantum efficiency (DQE), which is the most important imaging performance. In this paper, the DQE performance of both folded and conventional detector structures is analyzed by incorporating the quantum noise due to random charge carrier trapping in the photoconductor layer in the cascaded linear system model. An analytical expression for the variance of incomplete charge collection in folded structure is also developed. The optimum values of photoconductor layer thickness and spacing between electrodes for maximizing the DQE under various combinations of exposure, electronic noise and charge carrier transport parameters are investigated. The folded structure provides a design flexibility for achieving DQE higher than 0.7 by adjusting the distance between electrodes without compromising the quantum efficiency while the maximum possible DQE in conventional structure can be even below 0.3 for certain values of material and detector parameters.