射頻濺鍍氧化鋅在矽基板上之發光二極體特性研究

Abstract

本研究論文在探討利用射頻濺鍍系統製作氧化鋅/矽發光二極體元件與特性量測，分成三部分論述，第一部分是介紹射頻濺鍍系統原理與材料分析，第二部分是氧化鋅/矽發光二極體製作與電性和光學量測，第三部分是四種元件結構比較以及二氧化矽/n型矽介面反轉層穿隧電流模擬。首先，本文敘述利用射頻濺鍍系統成長氧化鋅，並且使用PL、XPS、UPS等量測技術，分析氧化鋅之成分。從PL結果得知晶體激發出中心位置在384nm，半高寬為26nm之紫外光，另一個中心位置在607nm，得知為氧化鋅之缺陷螢光頻譜，而由XPS、UPS材料分析得知氧化鋅/矽介面結構之能帶位置。吾人以上述射頻濺鍍系統製作氧化鋅/矽發光二極體元件，並量測其電壓—電流特性、電激發光頻譜、電容—電壓特性，將結果比較發現原生氧化層會影響ZnO/SiOx/p-Si、ZnO/p-Si發光二極體的導帶到價帶的躍遷以及透過I-V特徵曲線我們觀測到 ZnO/SiOx/n-Si在10mA發光的偏壓比起ZnO/SiOx/p-Si 10mA發光的偏壓值高出約1V，此驅動電壓之位移，不僅顯示n/p型Si之費米能級(Fermi level)差異，也說明白光機制乃來自ITO之電子與主動層本質缺陷之輻射結合。吾人利用電容電壓量測與SiOx/n-Si介面反轉層穿隧電流模擬計算少數載子的濃度分佈以及因穿隧效應所形成的穿隧電流密度。

In this thesis, the fabrication and characterization of ZnO/Si light emitting diode (LED) using radio frequency RF sputtering are presented. First, the theory of RF Sputtering system followed by material analysis is introduced. Second, the ZnO/Si LED devices are fabricated and measured. Last, the results with four different structures are compared and SiOx/n-Si interface inversion layer tunnel current are simulated.From the PL analysis pumped by a 325nm He:Cd laser, a peak emission wavelength at 384nm with a full width at half maximum (FWHM) of 26nm are and a peak emission wavelength at 607nm are observed. From the XPS and UPS data analysis, we identify the material binding energy position and the calculate interface band alignment.The ZnO/Si LED was fabricated by the RF sputtering system. The measured of I-V characteristics, EL spectra, and C-V characteristics show that native oxide layer influence the excitation of ZnO/SiOx/p-Si and ZnO/p-Si EL spectra from conduction band to valence band. The turn-on voltages of devices on p-Si are found 1V smaller than those of the devices on n-Si, which shows the Fermi level difference of p-Si and n-Si, also describes the broad band white light emission is owing to the nonoradiation combination of the electrons from ITO with the intrinsic defect of ZnO thin film.With the measured C-V characteristic measurements, and the simulated transmission tunneling current across SiOx/n-Si potential barriers, the minority carrier concentration and the tunneling current density are calculated.