  The semiconductor tracker (SCT) is one of the tracking systems for charged
particles in the ATLAS detector. It consists of 4088 silicon strip sensor
modules. During Run 2 (2015$-$2018) the Large Hadron Collider delivered an
integrated luminosity of 156 fb$^{-1}$ to the ATLAS experiment at a
centre-of-mass $pp$ collision energy of 13 TeV. The instantaneous luminosity
and pile-up conditions were far in excess of those assumed in the original
design of the SCT detector. Due to improvements to the data acquisition system,
the SCT operated stably throughout Run 2. It was available for 99.9% of the
integrated luminosity and achieved a data-quality efficiency of 99.85%.
Detailed studies have been made of the leakage current in SCT modules and the
evolution of the full depletion voltage, which are used to study the impact of
radiation damage to the modules.
