Development of an InGaAs SPAD 2D array for flash LIDAR

An InGaAs Single-Photon Avalanche Photodiode (SPAD) array and a hybrid photon-counting image sensor have been developed for time-resolved applications in the near infrared region, especially for Flash LIDAR. The implemented array has a 100 μm pitch 32×32 matrix, and the active area in each pixel has a diameter of 12 μm. A dedicated read-out IC incorporates an active quenching and recharge circuit, and an in-pixel time-to-digital converter with 318 ps resolution for providing stable Geiger-mode operation of the InGaAs SPAD pixels and a simultaneous time-resolving function. The uniformity of the electrical field in the entire two-dimensional area is one of the key characteristics as it affects most performance parameters. The breakdown voltage mapping revealed the SPAD array has an excellent uniformity. Full characterizations of dark count rate, photon detection probability, and timing jitter were performed and will be discussed. Methods of suppressing afterpulses were examined by utilizing an adjustable hold-off function. The results showed that the function worked effectively to reduce the afterpulse probability. Finally we prove that the InGaAs SPAD image sensor has the capability of accurate timing detection for constructing a flash LIDAR in the near future.