Device model for pixelless infrared image up-converters based on polycrystalline graphene heterostructures

摘要

We develop a device model for pixelless converters of far/mid-infraredradiation (FIR/MIR) images into near-infrared/visible (NIR/VIR) images. Theseconverters use polycrystalline graphene layers (PGLs) immersed in the van derWaals (vdW) materials integrated with light emitting diode (LED). The PGLserves as an element of the PGL infrared photodetector (PGLIP) sensitive to theincoming FIR/MIR due to the interband absorption. The spatially non-uniformphotocurrent generated in the PGLIP repeats (mimics) the non-uniformdistribution (image) created by the incident FIR/MIR. The injection of thenonuniform photocurrent into the LED active layer results in the nonuniformNIR/VIR image reproducing the FIR/MIR image. The PGL and the entire layerstructure are not deliberately partitioned into pixels. We analyze thecharacteristics of such pixelless PGLIP-LED up-converters and show that theirimage contrast transfer function and the up-conversion efficiency depend on thePGL lateral resistivity. The up-converter exhibits high photoconductive gainand conversion efficiency when the lateral resistivity is sufficiently high.Several teams have successfully demonstrated the large area PGLs with theresistivities varying in a wide range. Such layers can be used in the pixellessPGLIP-LED image up-converters. The PGLIP-LED image up-converters cansubstantially surpass the image up-converters based on the quantum-wellinfrared photodetector (QWIP) integrated with the LED. These advantages are dueto the use of the interband FIR/NIR absorption and a high photoconductive gainin the GLIPs.