Ultraviolet-visible detectors formed with wide band-gap Si-O nanostructures

• Main Authors: Chih-Yao Fang, 枋志堯
• Other Authors: Shing-Chung Wang
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/96801650433630713452

碩士 === 國立交通大學 === 光電工程系所 === 94 === In this thesis, we constructed ultraviolet-visible detectors with wide band-gap Si-O nanostructures. The inductively coupled plasma chemical vapor deposition (ICPCVD) was employed to synthesize three-dimensional Si nanocrystals (NCs) within mesoporous silica films. ICP makes reactive species own highly mobile and bond with pore-wall well, therefore, efficiently construct 3D Si NCs/silica arrays. The mean density of ICP-synthesized NCs is as high as 2.5x1018/cm3. Surface states of the resulting Si NCs/silica arrays initiate blue-white photoluminescence (PL). The specific interfacial bond-induced wide-bandgap electronic structure in Si-O nanostructured film significantly enhances the light extraction efficiency and the conduction of photoexcited carriers. We demonstrated efficient ultraviolet-visible photodiodes with blue band-gap Si-O nanostructures as capping layers on p-type silicon substrates by thin film technology. The capping layer is consisted of three-dimensional array of Si nanocrystals embedded in a mesoporous silica matrix. Hole charging in Si-O nanostructures due to photoionization of electrons forms positively charged capped layers. This occurrence enhances reverse bias of positive voltage so as to increase reverse photocurrents with responsivity of 0.2-0.9 A/W or gain of 1.4-2 in the range of 320-700 nm, in a somewhat avalanche manner, but inversely screens forward bias of negative voltage, leading to saturating forward photocurrents.