Ultraviolet, visible and near infrared photoresponse of SiO2/Si/SiO2 multilayer system into a MOS capacitor

In this paper, we report on the photoresponse properties of a SiO2/Si/SiO2 multilayer (ML) system deposited at 500 °C and integrated into a metal-oxide-semiconductor structure (Al/ML/p-Si) without any further thermal annealing. High contents of elemental Si (Si0) revealed by the XPS measurements suggests the formation of amorphous Si-nanoclusters (a-Si ncls) within the ML. Dark and illuminated I–V curves of the device indicate its sensitivity to ultraviolet, visible and near infrared light under applied bias and at 0 V. In addition, we observed variation of the spectral response and the external quantum efficiency as a function of the electrode size. At 0 V, the device illuminated with a wavelength at 550 nm exhibits a maximum external quantum efficiency of 0.95% and a spectral response of 4.1 mA/W. This photoresponse has been ascribed to photon absorption in SiO2 sub-band states created by the a-Si ncls and defects formed by the excess Si inside the SiO2/Si/SiO2 multilayers.