Device performance is in most cases connected to the materials quality. In many cases, high quality materials are available, but at a cost that is commercially not viable. We have been working on improving the quality of germanium for use as a virtual substrate for III-V semiconductor materials and for active silicon-based photonic devices. Germanium as a virtual substrate would enable low cost, high efficiency solar cells as will be presented in one example. An example for advanced germanium based devices are single photon detectors, operating at room temperature in the near infrared.