Design And Performance Study Of Narrow Band Near-infrared Photodetectors Based On Silicon Micro-holes Array

Narrow band near-infrared?NIR?photodetectors show a great potential application in biomedicine fields due to its high sensitivity to specific wavelengths,such as clinical diagnosis,treatment equipment or wearable functional monitoring equipment and so on.However,NIR photodetectors are mainly limited by expensive filters with complex optical system and its integration.In this dissertation,a novel high-performance,easy integration narrow-band NIR photodetector based on Si micro-holes heterojunction will be constructed.The design,fabrication and application in pulse monitoring of the NIR photodetectors was systematically studied.Silicon micro-holes array/graphene?Si MHs/Gr?Schottky diode?SD?,a good compatibility with complementary metal oxide semiconductor?CMOS?technique,was firstly chosen to construct the narrow band NIR photodetectors,and then the mechanism for narrow-band NIR response was systematically explored.The optimization of the heterojunction narrow band NIR response was then realized based on investigating the influence between the device performances with silicon trapping structures.Furthermore,the narrow-band NIR photodetectors was used in pulse signal monitoring and then the strong resistance to ambient light interference was significantly achieved.The main research contents are as follows:?1?The mechanism for self-filtered and visible-blind narrow-band NIR response of the Si MHs/Gr SD was elucidated by using Silvaco Technology Computer Aided Design?TCAD?to study relations between the light absorption characteristics and Si thickness and the collection of photogenerated carriers.The optimization of the device narrow-band NIR response was then studied based on silicon trapping structures,such as the shape,size of the silicon micro-holes.?2?The silicon micro-holes array was fabricated by using lithography and inductively coupled plasma etching?ICP?methods,and then Si MHs/Gr SD was constructed by using wet-transferred graphene as Schottky contact electrode based on above-mentioned optimization design.It is found that the resultant SD shows a self-filtered and,visible blind NIR narrow band response,with a peak response at around 1064 nm and,a half peak width of 96 nm,a detectivity up to 9.68×10¹² Jones and a responsivity approaching to 122 m A/W,which are higher than silicon/graphene Schottky diode by two orders of magnitude.?3?Based on photo plethysmo graphy?PPG?pulse monitoring principle,a heart-rate measurement system consisting of a Si MHs/Gr,980 nm light-emitting diode and amplifier was set up to realize the heart rate detection.The obtained heart-rate is comparable to that of commercial PPG system.Furthermore,the test system exhibits a good resistance to the ambient light interference.The results pave a way for design of a novel narrow band NIR photodetectors and exploring promise applications in the field of pulse signal monitoring against ambient light interference.