DMAPS Monopix developments in large and small electrode designs

TL;DR

This paper discusses the development and characterization of two types of DMAPS sensors, LF-Monopix1 and TJ-Monopix1, designed for high-radiation environments like the HL-LHC, highlighting their different electrode designs and performance after irradiation.

Contribution

It presents the design, implementation, and comprehensive testing of two DMAPS sensors with distinct electrode architectures for high-radiation applications.

Findings

LF-Monopix1 has a homogeneous electric field and short drift distances.

TJ-Monopix1 achieves low noise with small capacitance and full depletion.

Both sensors perform reliably before and after irradiation.

Abstract

LF-Monopix1 and TJ-Monopix1 are depleted monolithic active pixel sensors (DMAPS) in 150 nm LFoundry and 180 nm TowerJazz CMOS technologies respectively. They are designed for usage in high-rate and high-radiation environments such as the ATLAS Inner Tracker at the High-Luminosity Large Hadron Collider (HL-LHC). Both chips are read out using a column-drain readout architecture. LF-Monopix1 follows a design with large charge collection electrode where readout electronics are placed inside. Generally, this offers a homogeneous electrical field in the sensor and short drift distances. TJ-Monopix1 employs a small charge collection electrode with readout electronics separated from the electrode and an additional n-type implant to achieve full depletion of the sensitive volume. This approach offers a low sensor capacitance and therefore low noise and is typically implemented with small pixel size. Both detectors have been characterized before and after irradiation using lab tests and particle beams.