HgCdTe APDs detector developments for high speed, low photon number and large dynamic range photo-detection

HgCdTe Avalanche Photo Diodes (APDs) are developed at CEA/Leti to enable applications that require the detection of information contained in a low number of photons in each spatial and/or temporal bin, such as LiDAR and free space optical communications. The requirements for such detectors are strongly application dependent, which is why both the HgCdTe APD technology and the proximity electronics, used to extract the detected photocurrent, needs to be optimized for each application. The present communication reports results obtained from the development of detectors for high dynamic range LiDAR applications, made within the scope of the H2020 project HOLDON, and high data rate FSO, made in collaboration with Mynaric Lasercom AG. For FSO applications, we have measured 10 GHz bandwidth at unity gain for APDs with 10 μm diameter. At higher APD gain and diameter, the BW is presently limited by carrier transit and by resistance-capacitance product in small and large area APDs, respectively. For LiDAR we have developed APDs with an made of an array of diodes in parallel with a diameter up to 200 μm and large avalanche gain, M<100, that will be hybridized with a dedicated CMOS amplifier. This circuit was designed to enable photon shot noise limited linear detection over a dynamic range of 6 order of magnitude of signal for observation times ranging from ns up to μs. First characterizations made at unity APD gain shows that the HOLDON detector will meet most of the required performance parameters in terms of sensitivity and linear dynamic range.