Recent technological developments on LGAD and iLGAD detectors for tracking and timing applications

Abstract

This paper reports the last technological development on the Low Gain Avalanche Detector (LGAD) and introduces a new architecture of these detectors called inverse-LGAD (iLGAD). Both approaches are based on the standard Avalanche Photo Diodes (APD) concept, commonly used in optical and X-ray detection applications, including an internal multiplication of the charge generated by radiation. The multiplication is inherent to the basic n ++ -p + -p structure, where the doping profile of the p + layer is optimized to achieve high field and high impact ionization at the junction.The LGAD structures are optimized for applications such as tracking or timing detectors for high energy physics experiments or medical applications where time resolution lower than 30 ps is required. Detailed TCAD device simulations together with the electrical and charge collection measurements are presented through this work.

Fabrication and performance of AC-coupled LGADs

“…A further example is provided by the silicon microstrip sensors that implement the gain layer under the strip [6]: such devices show multiplication only in a fraction of the area, i.e., in the center of the strip. A way to circumvent such problem can be the placement of a large uniform pad on the opposite side of the patterned electrodes [7,8]. However, as mentioned above, also in this case the wafer must be thick enough as to be processed in a standard clean-room (i.e., 200-300 µm thick, depending on the wafer diameter) and thus the fast timing properties of the LGADs are compromised.…”

Imaging and time stamping of photons with nanosecond resolution in Timepix based optical cameras

“…The amplification can be achieved outside of the sensor using an image intensifier, as described above or, alternatively, inside the sensor. Sensors with internal amplification are based on technologies such as SPAD (single photon avalanche devices) [28] and LGAD (low gain avalanche devices) [29,30], which have a multitude of applications, including high-energy physics. Advances in the CMOS technology are enabling integration of these devices in to pixelated silicon sensors.…”

Multiplication onset and electric field properties of proton irradiated LGADs

“…LGADs [3,4,5,6,7,8]. The development of LGADs is considerably advanced, with ATLAS and CMS already foreseeing the use of LGADs in their detectors [9,10,11].…”