Oxidized Nano-Porous-Silicon Buffer Layers for Suppressing the Visible Photoresponsivity of ZnO Ultraviolet Photodetectors on Si Substrates

Abstract EN

This paper demonstrated the fabrication and optoelectronic characteristics of ZnO ultraviolet (UV) photodetectors fabricated on Si substrates with oxidized nano-porous-Si (ONPS) buffer layers.

ONPS layers were prepared on the surfaces of Si substrates by use of an electrochemical anodization technique following a rapid-thermal-oxidation process.

Experimental results indicated that application of ONPS buffer layers not only improved the crystallinty of the deposited ZnO thin films but also greatly restricted the visible-to-infrared photoresponse that was generated from the light absorption of Si substrates.

The developed ZnO-on-ONPS photodiodes achieved high photoresponsivity for the incident UV light of 300 ∼ 400 nm and got a large photo-to-dark current ratio up to 104 at wavelength of 375 nm under a bias of 5 V.

Therefore, ZnO on ONPS provides a highly potential approach for the development of low-cost visible-blind UV photodetectors.