The important contribution of photo-generated charges to the silicon nanocrystals photo-charging/discharging-response time at room temperature in MOS-photodetectors

• Investigation into the photogenerated changes that occur in the capacitance–voltage (C–V) characteristics of Metal-Oxide-Semiconductor (MOS) photodetector, having a silicon nanocrystals (Si-ncs) embedded in SiOx=1.5 tunnel oxide layers with a very small area.
• Demonstration of the ability of photo-C-V measurements to study the charge state of Si-ncs in an MOS photodetectors and identify the tunneling phenomena between the semiconductor and the Si-ncs layer.
• Demonstrated the important contribution of photo-generated charges to the Si-ncs charging/discharging photo-response time.

The results are reported of a detailed investigation into the photogenerated changes that occur in the capacitance–voltage (C–V) characteristics of Metal-Oxide-Semiconductor (MOS) photodetector, having a silicon nanocrystals (Si-ncs) embedded in SiOx=1.5 tunnel oxide layers. In order to study the influence of photon energy on charging/discharging photo-response of nanocrystal-based MOS structures, we have examined photo-capacitance-voltage (photo-CV) measurements at both light intensities 45 μW and 75 μW and wavelengths 436 nm and 595 nm. The photo-CV measurements indicate the important contribution of photo-generated charges to the charging/discharging mechanism. The (Si-ncs) charging/discharging photo-response time is evaluated to be 300 s at wavelength of 595 nm for 75 μW optical power at room temperature. This response time is influenced by the photogenerated-holes lifetime in the Si-ncs.