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We report on the observation of cyclotron resonance induced photocurrents, excited by continuous wave terahertz radiation, in a 3D topological insulator (TI) based on an 80 nm strained HgTe film. The analysis of the photocurrent formation is supported by complimentary measurements of magneto-transport and radiation transmission. We demonstrate that the photocurrent is generated in the topologically protected surface states. Studying the resonance response in a gated sample we examined the behavior of the photocurrent, which enables us to extract the mobility and the cyclotron mass as a function of the Fermi energy. For high gate voltages we also detected cyclotron resonance (CR) of bulk carriers, with a mass about two times larger than that obtained for the surface states. The origin of the CR assisted photocurrent is discussed in terms of asymmetric scattering of TI surface carriers in the momentum space. Furthermore, we show that studying the photocurrent in gated samples provides a sensitive method to probe the effective masses and the mobility of 2D Dirac surface states, when the Fermi level lies in the bulk energy gap or even in the conduction band.

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sensor pixel geometry. The MCM construction is described, and the imaging performance of the different detectors is shown. As readout system a newly developed USB system has been used.

A functionalization is required for calcium phosphate-based bone substitute materials to achieve an entire bone remodeling. In this study it was hypothesized that a tailored composite of tricalcium phosphate and a bioactive glass can be loaded sufficiently with rhBMP-2 for functionalization. A composite of 40 wt% tricalcium phosphate and 60 wt% bioactive glass resulted in two crystalline phases, wollastonite and rhenanite after sintering. SEM analysis of the composite's surface revealed a spongious bone-like morphology after treatment with different acids. RhBMP-2 was immobilized non-covalently by treating with chrome sulfuric acid (CSA) and 3-aminopropyltriethoxysilane (APS) and covalently by treating with CSA/APS, and additionally with 1,1'-carbonyldiimidazole. It was proved that samples containing non-covalently immobilized rhBMP-2 on the surface exhibit significant biological activity in contrast to the samples with covalently bound protein on the surface. We conclude that a tailored composite of tricalcium phosphate and bioactive glass can be loaded sufficiently with BMP-2.