Performance of CMOS pixel sensor prototypes in ams H35 and aH18 technology for the ATLAS ITk upgrade

• Main Authors: Kiehn, Moritz, Di Bello, Francesco Armando, Benoit, Mathieu, Mohr, Raimon Casanova, Chen, Hucheng, Chen, Kai, S, Sultan D. M, Ehrler, Felix, Ferrere, Didier, Frizell, Dylan, Sevilla, Sergio Gonzalez, Iacobucci, Giuseppe, Lanni, Francesco, Liu, Hongbin, Merlassino, Claudia, Metcalfe, Jessica, Miucci, Antonio, Peric, Ivan, Prathapan, Mridula, Schimassek, Rudolf, Barreto, Mateus Vicente, Weston, Thomas, Figueras, Eva Vilella, Weber, Alena, Weber, Michele, Wong, Winnie, Wu, Weihao, Zaffaroni, Ettore, Zhang, Hui, Zhang, Matt
• Format: Journal Article
• Language: English
• Published: 08-06-2020
• Subjects: Physics - Instrumentation and Detectors
• DOI: 10.48550/arxiv.1807.05953

Pixel sensors based on commercial high-voltage CMOS processes are an exciting
technology that is considered as an option for the outer layer of the ATLAS
inner tracker upgrade at the High Luminosity LHC. Here, charged particles are
detected using deep n-wells as sensor diodes with the depleted region extending
into the silicon bulk. Both analog and digital readout electronics can be added
to achieve different levels of integration up to a fully monolithic sensor.
Small scale prototypes using the ams CMOS technology have previously
demonstrated that it can achieve the required radiation tolerance of
$10^{15}~\text{n}_\text{eq}/\text{cm}^2$ and detection efficiencies above
$99.5~\%$. Recently, large area prototypes, comparable in size to a full
sensor, have been produced that include most features required towards a final
design: the H35demo prototype produced in ams H35 technology that supports both
external and integrated readout and the monolithic ATLASPix1 pre-production
design produced in ams aH18 technology. Both chips are based on large
fill-factor pixel designs, but differ in readout structure. Performance results
for H35DEMO with capacitively-coupled external readout and first results for
the monolithic ATLASPix1 are shown.