Ultrafast optoelectronics in nanowire-based circuits

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.
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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.
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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.
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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.