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Optimizing photodiode-integrated SPR sensor chips based on n-i junctions
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DOI：10.1016/j.sna.2024.116159.png)
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Abstract
En 中文
Recently, we reported the successful fabrication of surface plasmon resonance (SPR) sensor chips integrated with a photodiode using glass/indium tin oxide (ITO)/n-type silicon (nSi)-intrinsic silicon (iSi)/titanium (Ti)/gold (Au) structures, capable of detecting changes in the environmental refractive index as small as 0.005 refractive index unit (RIU). These SPR sensor chips operate similarly to conventional SPR sensor chips with glass/Au or glass/Ti/Au structures. However, instead of measuring the magnitude of reflected light with respect to the incident angle of light to obtain the SPR curve-which represents the dependence of reflected light intensity on the incident angle-we measure the dependence of photocurrent on the incident angle. The slope of the SPR curve in this configuration is highly influenced by the n-i junction, represented by the nSi-iSi multilayer arrangement, with the position and width of the depletion region within the multilayer playing a significant role. In this study, we systematically investigated the impact of the depletion region width, controlled via the iSi layer thickness, on the slope of the SPR curve. The thickness of the ITO (200 nm), nSi (20 nm), Ti (10 nm), and Au (50 nm) layers were kept constant, while the iSi layer thickness was varied at 50, 80, 120, and 140 nm. Our results indicate that the sensor chip with the structure ITO (200 nm)/nSi (20 nm)-iSi (80 nm)/Ti (10 nm)/Au (50 nm) exhibits the optimal slope in the SPR curve, which is 2-3 times steeper than that of other configurations. This optimal SPR sensor chip improves the efficiency of our photodiode-integrated SPR sensor chips and can be utilized for water analysis processes.
Keywords:
Surface plasmon resonance
Photodiode-integrated SPR sensor
N-i junction
NSi-iSi multilayer
Journal
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4.9
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1.5W
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3.3W