Charge collection and efficiency measurements of the TJ-Monopix2 DMAPS in 180$\,$nm CMOS technology

TL;DR

This paper presents the design, fabrication, and testing of the TJ-Monopix2 monolithic CMOS pixel detector in 180nm technology, demonstrating promising charge collection, efficiency, and radiation tolerance for high-energy physics applications.

Contribution

It introduces a novel 180nm CMOS DMAPS with a large pixel matrix, low power design, and enhanced radiation tolerance through process modifications.

Findings

High hit detection efficiency in unirradiated modules

Successful charge collection and electrical characterization

Potential for high-radiation environments in particle physics

Abstract

Monolithic CMOS pixel detectors have emerged as competitive contenders in the field of high-energy particle physics detectors. By utilizing commercial processes they offer high-volume production of such detectors. A series of prototypes has been designed in a 180$\,$nm Tower process with depletion of the sensor material and a column-drain readout architecture. The latest iteration, TJ-Monopix2, features a large 2$\,$cm x 2$\,$cm matrix consisting of 512 x 512 pixels with 33.04$\,$um pitch. A small collection electrode design aims at low power consumption and low noise while the radiation tolerance for high-energy particle detector applications needs extra attention. With a goal to reach radiation tolerance to levels of $10^{15}\,1\,$MeV n$_\text{eq}\,$cm$^{-2}$ of NIEL damage a modification of the standard process has been implemented by adding a low-dosed n-type silicon implant across the pixel in order to allow for homogeneous depletion of the sensor volume. Recent lab measurements and beam tests were conducted for unirradiated modules to study electrical characteristics and hit detection efficiency.