A Silicon-Based Photosensor With Photosensitive Cavity Structure

This study proposes a novel photodiode with photosensitive cavity structure, realized by simple KOH isotropic etching and ion implantation technology. The main design concept is using the photosensitive surface of the cavity to capture the light rays of the sensing area, so as to further increase sensing performance. A TracePro simulation shows that the light capture effect of a single cavity structure is enhanced as the etch depth increases due to increase in surface sensing area. However, since the etch depth is limited by the wafer thickness, this research proposes to increase the surface area of the photodiode by using an array of micro-cavity units to improve the sensing efficiency while reducing the needed etch depth. The experimental results show that under the same light-receiving conditions, the sensitivity of the photodiode with a single cavity and a multi-cavity is higher than that of the general planar design, by about 20% and 16%. In addition, at a luminance of 0 nt to 80 × 10
³
nt, the linear adaptation rate (R
²
) of the linear fitted curve is larger than 0.99.