The CMS tracker collaboration has initiated a large material investigation and irradiation campaign to identify the silicon material and design that fulfills all requirements for silicon tracking detectors for the high-luminosity phase of the Large Hadron Collider (HL-LHC). A variety of silicon p-in-n and n-in-p test-sensors made from Float Zone, Deep-Diffused FZ and Magnetic Czochralski materials were manufactured by one single industrial producer, thus guaranteeing similar conditions for the production and design of the test-structures. Properties of different silicon materials and design choices have been systematically studied and compared. The samples have been irradiated with neutrons (1 MeV) and protons (23 MeV and 23 GeV) corresponding to maximal fluences as expected for several positions of detector layers in the future tracker. Irradiations with protons of different energies have been performed to evaluate the energy dependence of the defect generation in oxygen rich material. All materials have been characterized before and after irradiations, and throughout an annealing treatment The measurements performed on the structures include electrical sensor characterization, measurement of the collected charge injected with a beta source or laser light and bulk defect characterization. In this paper, a selection of results from the ongoing studies is presented.