Abstract
Optical crosstalk is one of major problems limiting the performance of focal plane arrays based on single photon avalanche diodes (SPADs). In this work, for the first time the crosstalk characteristics of a 4H-SiC SPAD linear array are studied, which is based on a real-time dual channel data acquisition method. It is found that SiC SPAD array exhibits similar crosstalk probability compared with those of InGaAs-based SPAD arrays, which can be effectively reduced by trench isolation between adjacent pixels or by lowering overbias. The average time required for forming a crosstalk event is determined between 7 and 10 ns. As a result, active time-gated operation scheme can be applied for reducing crosstalk.
Highlights
Nowadays, ultraviolet (UV) focal plane array (FPA) based on SiC single photon counting avalanche photodiodes (SPADs) has attracted much attention due to its potential to replace traditional microchannel plate (MCP) based image intensifiers, which are key components for many cuttingedge applications, such as missile plume detection and tracking, solar physics as well as chemical/biological agent detection [1], [2], [3]
It is found that SiC SPAD array exhibits similar crosstalk probability compared with those of InGaAs-based SPAD arrays, which can be effectively reduced by trench isolation between adjacent pixels or by lowering overbias
The above result means that the formation time of a crosstalk in the SiC SPAD array is mostly distributed between 7–10 ns, which is very close to the Tobs value of 10 ns found in Si SPAD array systems [7]
Summary
Ultraviolet (UV) focal plane array (FPA) based on SiC single photon counting avalanche photodiodes (SPADs) has attracted much attention due to its potential to replace traditional microchannel plate (MCP) based image intensifiers, which are key components for many cuttingedge applications, such as missile plume detection and tracking, solar physics as well as chemical/biological agent detection [1], [2], [3]. To improve imaging resolution and quantum efficiency, there is continuous effort to enhance fill factor of each pixel and reduce pixel spacing in FPA design. In the case of an InGaAs/InP SPAD array with a pixel spacing of 100 μm, the crosstalk probability between two neighboring SPADs has been determined ∼2%, and the total. Many experiments have shown that optical crosstalk is a serious counting error factor in highly integrated SPAD FPAs [9], [10], [11]. Linear arrays based on SiC UV SPADs are designed and fabricated with and without trench isolation. It is determined that SiC SPAD array exhibits similar crosstalk probability compared with those of InGaAs-based SPAD arrays at comparable pixel spacing. The work may provide a useful guidance for design of FPAs based on SiC UV SPADs
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