鑽石包覆矽量子點之研究

Abstract

鑽石具有高硬度、能隙大等優異材料性質，而矽量子點有長波長之發光特性，結合兩者之優點將深具應用潛力。本論文以電漿製程製作包覆於鑽石中之矽量子點結構，並探討鑽石品質與矽量子點的發光行為。 以低壓化學氣相沉積系統(Low Pressure Chemical Vapor Deposition, LPCVD)在多晶與單晶鑽石基板上沉積50 nm的矽薄膜，然後在微波電漿輔助沉積系統(Microwave Plasma-assisted Chemical Vapor Deposition, MPCVD)中以氫電漿將矽蝕刻至結晶矽量子點形式後，接著成長CVD鑽石將矽量子點包覆於鑽石中。以掃描式電子顯微鏡(Scanning Electron Microscope, SEM)、微拉曼光譜(Micro Raman Spectroscopy)、X光繞射儀(X-Ray Diffraction, XRD)、光致發光光譜(Photoluminescence Spectrometer, PL)和穿透式電子顯微鏡 (TEM)分析矽量子點與鑽石之性質。 CVD鑽石與單晶鑽石基板是同質磊晶關係且矽量子點對鑽石品質影響不大。矽量子點之PL訊號範圍為970~1100 nm。HRTEM影像顯示矽量子點尺寸小於10 nm。

Diamond has high hardness, a wide band gap, and other excellent properties, while Si quantum dots (QDs) has long wavelength luminescence. Combing Si QDs with diamond may have advantages in many potential applications. In this thesis, the structure of silicon QDs coated with diamond was fabricated by using plasma processing. The results of quality of diamond and luminescence properties of Si QDs are presented. A 50 nm silicon film was initially deposited on diamond substrate by low pressure chemical vapor deposition, followed by hydrogen plasma etching of the Si film to form crystalline Si QDs in a microwave plasma-assisted chemical vapor deposition (MPCVD) system. MPCVD of diamond was subsequently carried out to fully cover the Si QDS. Structural and optical properties were measured with scanning electron microscopy (SEM)、micro Raman Spectroscopy、X-ray diffraction(XRD)、photoluminescence (PL) spectroscopy, and transmission electron microscopy (TEM)。 The results show that CVD diamond is grown in homoepitaxy with diamond substrate, and diamond quality is negligibly affected by Si QDs. The PL signal of Si QDs is 970 ~ 1100 nm. HRTEM images present the size of Si QD smaller than 10 nm.