Effect of Surface Structure on the Sensitivity of Fluorescence-Enhanced Si Photodiodes for Ultraviolet C Light Measurement

Abstract

This study aims to significantly enhance the sensitivity of a fluorescence-enhanced Si photodiode (FE-PD) to ultraviolet C-ray (UVC) light by optimizing the three-dimensional surface shape of the phosphor attached to the Si-PD, thereby increasing the UVC detection sensitivity. In the sensitivity-enhanced FE-PD, the surface of the red fluorescent acrylic resin phosphor affixed to the Si-PD was carved with a stripe and grid at varying depths, and triangular roofs and square pyramids at various angles. The effects of roughening the phosphor surfaces with diamond abrasives of varying mesh sizes—ranging from #180 to #3000—were comparatively evaluated against those with flat, mirror-like surfaces. As observed, the UVC light sensitivity of the FE-PD using a surface-carved triangular roofs and square pyramids at angle of 70° exhibited significant improvements compared to the Si-PD with both non-modified and mirror-polished phosphors. Thus, the FE-PD with a surface-modified phosphor is a promising candidate for UVC light sensor.