We explore materials and morphologies of semiconducting nanowires to demonstrate that the diversified lateral and coaxial architectures of semiconducting nanowires allow building the smallest semiconducting, fully integrated ultrafast photoswitches.[12] We demonstrate that a linear grading of the indium content along InGaN-nanowires from GaN to InN introduces an internal electric field evoking a photocurrent on a picosecond time-scale.[3] Consistent with quantitative band structure simulations we observe a sign change in the measured photocurrent as a function of photon flux. This negative differential photocurrent opens the path to a new type of nanowire-based photodetector. Moreover, we clarify how the nature and speed of photoelectric excitations depend on the dimensionality of the internal electronic systems. In particular, we demonstrate a dimensionally confined propagation of photogenerated charge carriers in the 2D quantum wells of core-shell GaAs-AlGaAs-nanowires.[4] We further demonstrate how photo-thermoelectric currents and THz-generation mechanisms can dominate the ultrafast optoelectronic response of semiconducting nanowires. Our work demonstrates that single semiconducting nanowires can be integrated into high-speed stripline circuits for an information processing on a picosecond time-scale.