Contact printing of compositionally graded CdSxSe1-x nanowire parallel arrays for tunable photodetectors

Spatially composition-graded CdSxSe1-x (x = 0-1) nanowires are grown and transferred as parallel arrays onto Si/SiO2 substrates by a one-step, directional contact printing process. Upon subsequent device fabrication, an array of tunable-wavelength photodetectors is demonstrated. From the spectral photoconductivity measurements, the cutoff wavelength for the device array, as determined by the bandgap, is shown to cover a significant portion of the visible spectrum. The ability to transfer a collection of crystalline semiconductor nanowires while preserving the spatially graded composition may enable a wide range of applications, such as tunable lasers and photodetectors, efficient photovoltaics, and multiplexed chemical sensors.