Abstract
A single-photon avalanche diode (SPAD) with enhanced near-infrared (NIR) sensitivity has been developed, based on 0.18 μm CMOS technology, for use in future automotive light detection and ranging (LIDAR) systems. The newly proposed SPAD operating in Geiger mode achieves a high NIR photon detection efficiency (PDE) without compromising the fill factor (FF) and a low breakdown voltage of approximately 20.5 V. These properties are obtained by employing two custom layers that are designed to provide a full-depletion layer with a high electric field profile. Experimental evaluation of the proposed SPAD reveals an FF of 33.1% and a PDE of 19.4% at 870 nm, which is the laser wavelength of our LIDAR system. The dark count rate (DCR) measurements shows that DCR levels of the proposed SPAD have a small effect on the ranging performance, even if the worst DCR (12.7 kcps) SPAD among the test samples is used. Furthermore, with an eye toward vehicle installations, the DCR is measured over a wide temperature range of 25–132 °C. The ranging experiment demonstrates that target distances are successfully measured in the distance range of 50–180 cm.
Highlights
Advanced driver assistance systems (ADASs) have been designed and developed to make automobiles more comfortable, and to reduce the number of traffic accidents [1].Forward collision warning (FCW), autonomous emergency breaking (AEB), and pedestrian detection, to cite a few examples, rely on various technologically advanced sensors
Millimeter-wave RADARs and stereo-vision cameras remain the key sensors of choice
These sensors do have limitations, so a number of advanced driver assistance systems (ADASs) implementations rely on the data fusion of two or more sensors
Summary
Advanced driver assistance systems (ADASs) have been designed and developed to make automobiles more comfortable, and to reduce the number of traffic accidents [1].Forward collision warning (FCW), autonomous emergency breaking (AEB), and pedestrian detection, to cite a few examples, rely on various technologically advanced sensors. Millimeter-wave RADARs and stereo-vision cameras remain the key sensors of choice These sensors do have limitations, so a number of ADAS implementations rely on the data fusion of two or more sensors. In this context, we have been developing an optical long-range sensor technology based on the time-of-flight (TOF) principle for next-generation ADASs [2,3,4]. We have been developing an optical long-range sensor technology based on the time-of-flight (TOF) principle for next-generation ADASs [2,3,4] This light detection and ranging (LIDAR) sensor offers a very good balance of overall performance in terms of spatial (image) resolution, field-of-view, precision, and depth range. The device, referred to as a single-photon avalanche diode (SPAD), is a highly sensitive photodetector capable of outputting a precise and digital trigger signal upon the detection of ultralow-power signals, down to Sensors 2016, 16, 459; doi:10.3390/s16040459 www.mdpi.com/journal/sensors
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