利用寬能隙矽氧奈米結構物製作紫外到可見光之光偵測器

Abstract

在本論文中，我們利用寬能隙矽氧奈米結構物建構紫外到可見光之光偵測器。感應耦合式電漿化學氣相沉積系統將矽量子點合成至奈米介孔洞二氧化矽中。感應耦合式電漿使反應氣體具有高擴散率及高解離率的特性，使得矽量子點能有效率地沈積在孔壁上，因此，形成許多矽量子點/二氧化矽的結構，其密度可高達2.5x1018/cm3。矽量子點/二氧化矽所形成的表面態可發出有效率的光激發螢光(PL)。藉由此介面鍵結形成寬能隙矽氧奈米結構物的特性可以增強發光效率以及光激發載子的導電性。 我們用薄膜技術在p型矽基板上製作寬能隙矽氧奈米結構物的方法，建構有效率的紫外光到可見光之光偵測器。此奈米結構物是由矽量子點/二氧化矽所構成。由於光激發所游離的電子會使得殘餘的電洞儲存於矽氧奈米結構物中而形成正電荷層。這樣的行為會增強逆向偏壓下光電流的產生以及些微的雪崩效應，在波長為320-700nm範圍內，其光響應度為0.2-0.9A/W，增益為1.4-2。但相對地，在順向偏壓下會造成屏蔽效應，導致順向飽和電流。

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.