Tunable optical loss and multi-band photodetection based on tin doped CdS nanowire

Inorganic semiconductor nanowires is the fundamental connector in on-chip nano-photonic circuitry systems. The optical loss during light propagation as the key parameter influence its performance as waveguide. So accurate determination of optical loss is imperative for the optical information communication between different active and passive optical components. In this work, pumping power dependent optical loss along the tin doped CdS nanowires were investigated. By calculating the out-coupling photoluminescence intensity from one end of a nanowire with respect to the propagation length, the attenuation coefficient of the near band edge emission changed from 0.097 μm⁻¹ to 0.061 μm⁻¹ with the laser power increases. Similarly, with the increasing of excitation power, the attenuation coefficient of the defects related emission can be tuned from 0.098 μm⁻¹ to 0.067 μm⁻¹. In addition, the activation energy is determined to be 34.29 meV by the low temperature photoluminescence experiment, demonstrating the main carriers decay channel is exciton recombination at room temperature (T = 300 K). Therefore, the individual tin doped CdS nanowire photodetector is fabricated and systematically testing. Under a low illumination intensity (142 μW/cm²@405 nm), the detector exhibit a high responsivity of 51.2 A/W, together with the gain of 313.3. Furthermore, the nanowire detector shows stable photos-witching and multi-band response characteristic. Based on the tunable optical loss and broad spectrum response property, the tin doped CdS nanowires used as waveguide or active material can be electively applied in integrated nanophotonic and optoelectronic systems.