Tip Avalanche Photodiode -- A new generation Silicon Photomultiplier based on non-planar technology

Abstract

The Silicon Photomultiplier (SiPM) is a mature photodetector concept that is applied in a variety of applications ranging from medical imaging to automotive LiDAR systems. Over the last few years, improvements of the sensor performance are gradually approaching to a saturation. In this work we present our new concept to overcome the intrinsic limitations of planar configurations of electrodes. Our non-planar technology is based on focusing and enhancing the electric fields by tip-like electrodes. The shape of the electric field and the lack of typical micro-cell edges, allows us to exclude cell separation boundaries and eliminate dead space around active cell areas. Our design provides a high-density micro-cell layout with a high geometric efficiency. It resolves the well-known trade-off between the detection efficiency and the dynamic range. The first "Tip Avalanche Photodiode" (TAPD) prototypes show a remarkable geometric efficiency above 80 % for a micro-cell pitch of 15 µm. This directly translates into a photon detection efficiency (PDE) record peak value of 73 % at 600 nm with respect to the state-of-the-art SiPMs. Moreover, the PDE remains above a value of 45 % up to a wavelength of 800 nm with another record value of 22 % at 905 nm. The reduced micro-cell capacity allows for a fast recovery time below 4 ns, which improves the operation at high photon rates. Overall, the TAPD is anticipated to be a very promising SiPM generation for various wide-spectral and high-dynamic-range applications in health science, biophysics, particle physics and LiDARs.