Performance studies of Belle II DEPFET Pixel Half-Ladders in Test Beams

In the momentary ongoing upgrade of the Japanese Flavor Factory (KEKB) to SuperKEKB for the Belle II experiment the luminosity targets a luminosity increase to 8 $\cdot$ 10${}^{35}$cm${}^{-2}$s${}^{-1}$, which is 40 times higher than the previous luminosity of the Belle experiment. In order to handle the increased data rate, a new detector design is mandatory. This was realized by adding an additional pixel detector to the vertex detector, based on DEPFET technology. The DEPFET pixels have a completely depleted silicon bulk and combine signal detection and amplification in a single chip. As part of a beam test campaign at DESY the influence on the the efficiency of different bulk biasing settings was tested on different half-ladders. The half-ladders used were final PXD modules with pixel sizes in the range of (55-85) $\times$ 55 $\mu$m${}^2$. The results from the beam test will be presented in this talk.