WE‐A‐201B‐03: Resistive Interface Layer for Flat‐Panel Imager (FPI) with Avalanche Gain

Purpose: The low dose performance of existing solid‐state flat panel imagers (FPI) are degraded by electronic noise. To overcome this problem, we have proposed a new FPI concept. It employs a structured Csl scintillator to convert incident x‐rays to optical photons, which is converted to amplified electronic signal by a thin (∼15 microns) amorphous selenium (a‐Se) photoconductor with avalanche multiplication gain. One critical component of this detector is the resistive interface layer (RTL) which provides protection of electrical breakdown under high electric field (>100V/um) required for avalanche multiplication. Method and Material: Using physics model and simulation, we estimated the desirable range of resistivity and thickness of RIL to a while maintaining good spatial resolution and image lag. Material deposition procedures were developed to achieve these RIL properties. Results: Our investigation found that RIL with resistivity in the range of 10̂10 to 10̂12 ohm‐cm and with thickness of 2 microns (with solution based deposition methods) could provide satisfactory imaging performance. RIL material based on mixing insulating polymers with conductive fillers provides great versatility for our purpose.