Photo-Sensitivity Enhancement of ${\rm HfO}_{2}$ -Based MOS Photodiode With Specific Perimeter Dependency Due to Edge Fringing Field Effect

On account of edge fringing field effect, deep depletion would happen and charge collection would be largely enhanced at edge. Hafnia (HfO₂)/SiO₂-stacked metal-oxide-semiconductor photodiode is proposed and perceived by analyzing the photocurrents with various elongated edge perimeter. This structure of HfO₂/SiO₂ exhibits an enhanced edge charge collection characteristic that could be applied to generate the considerable photocurrent in magnitude. Higher tunneling probability in the deeper depletion region at edge makes explicitly larger portion of current, pass through this area due to edge fringing field effect. Under illumination, photo-excited charge collection would be largely enhanced at the edge. Moreover, responsivity R and photosensitivity Ps, which were evaluative figures for photo-electrical applications, were examined and discussed. The slope mmbκ of photo-current versus irradiance curves reaches to 1.59 which is feasible for image sensor. These results are attributed to the enhanced edge-deep depletion absorption of light due to edge-fringing field effect.