  Sterile neutrinos in the keV mass range present a viable candidate for dark
matter. They can be detected through single $\beta$ decay, where they cause
small spectral distortions. The Karlsruhe Tritium Neutrino (KATRIN) experiment
aims to search for keV-scale sterile neutrinos with high sensitivity. To
achieve this, the KATRIN beamline will be equipped with a novel multi-pixel
silicon drift detector focal plane array named TRISTAN. In this study, we
present the performance of a TRISTAN detector module, a component of the
eventual 9-module system. Our investigation encompasses spectroscopic aspects
such as noise performance, energy resolution, linearity, and stability.
