Theory, design, and performance of low-blooming silicon diode array imaging targets

The phenomenon of increase in size of the image produced by a high intensity source is particularly troublesome in silicon diode array imaging devices. Although there are various causes for this "blooming", e.g., lens flare and beam pulling, the most prominent cause is the lateral diffusion of the excess minority carriers in the field-free region of the sensor array. When the diodes in the image are fully discharged in a time interval shorter than the frametime, the excess carriers diffuse to the adjacent diodes and cause an increase in the size of the image. It will be shown theoretically how blooming is related to the effective minority carrier lifetime which is a function of surface recombination velocity at the imaging side of the target, surface recombination velocity at the diode side of the target, and bulk minority carrier lifetime.