Optimization of charge collection efficiency in MSM photodetector

The effects of different geometries, heights and concentrations per unit area of gratings in the active region of a metal semiconductor metal photo-detector have been analyzed for enhanced charge collection through electromagnetic field analysis. Plots of the electric field amplitude as it propagates from the constricted grating region to a larger cross-section in the active region have been studied for comparison. This study shows that a hatched top cone shaped grating allows for maximum energy transfer into the active region, thus enhancing collection. The height for this structure is also a minimum over all structures, thus making the hatched cone the optimum design for enhanced collection. The cladding of such structures with SiO2 also appears to contribute to increased energy transfer into the substrate.