Stacked Homojunction Effects on Crosstalk and Response Resolution in CMOS Compatible Photodiode Arrays
Faculty of Computing, Health and Science
School of Engineering and Mathematics
Crosstalk between adjacent pixels has the potential to adversely affect the resolution of CMOS imaging arrays. The problem of crosstalk and loss of sensitivity with the conventional single junction photodiode is the lack of control of the direction of carrier diffusion. In this study, we have simulated the effect of a stacked gradient homojunction photodiode on crosstalk in CMOS compatible photodiode arrays. The five-layer stacked gradient homojunction photodiode, investigated in this study, shows one dimensional control of carrier transport towards the frontwall of the pixel, improving pixel carrier capture volume, which improves response resolution. Frontwall illumination has better crosstalk suppression than backwall illumination. The reverse is true for sensitivity, for which the back illuminated device shows superior sensitivity to that of other photodiode configurations previously studied. Increasing the epilayer thickness improves the sensitivity over a broader wavelength range but increases crosstalk.