Wavelength Selective Photodetectors Integrated on a Single Composition‐Graded Semiconductor Nanowire

Abstract Nanoscale wavelength sensitive photodetectors based on single nanostructures are of significance for realizing future integrated optoelectronic devices. In this work, wavelength selective photodetectors integrated on a single composition‐graded CdS_xSe_1−x nanowire are realized. The photodetectors show an obvious illumination wavelength related rectifying effect, which can be ascribed to the graded composition along the wire. By spatially resolved photocurrent imaging, it is shown that the photoresponse of composition‐graded photodetectors is not restricted to the near contact regions, but can be extended to the whole nanowire due to the active optical waveguide to the narrow bandgap contact. Furthermore, by fabricating multielectrodes at different sections of the composition‐graded nanowire, multi‐photodetectors with tunable wavelength response ranges and selective rectified ratio at different wavelengths are realized. This work provides a deeper understanding of the dynamics of photogenerated carriers in bandgap‐engineered nanostructure photodetectors and opens the path to promising potential applications in integrated photonic and optoelectronic devices.