三五族材料能隙可藉摻雜而改變，利用此材料製作發光二極體(Light-emitting Diode, LED)，其發光波段可以涵蓋紫外光到近紅外光區域，近年來已經應用在許多日常生活用品上，包含隱藏於筆記型電腦之背光源、汽車車燈、戶外大型看板、與室內照明。因氮化鎵材料本身磊晶成長過程中，量子井發光層內部累積自發極化場與壓電極化場，電子電洞波函數分離，降低電子電洞複合機率，造成整體發光效率下降。另外，元件在長時間操作時，發光波長受到熱效應紅移，也限制了LED在生物醫學上應用。
本研究利用雙聚焦型離子束(Focused Ion Beam, FIB)製作各種次微米之藍光LED，並針對製程參數對於元件外觀製作之影響做探討。有別其他研究團隊利用電子致發光(Cathodoluminescence, CL)量測氮化鎵陣列型奈米柱發光特性分析，此研究設計之薄片型LED可以單獨被拿來利用電激發量測其光電特性。
在變溫量測系統下，次微米尺寸LED之光電特性可利用光纖收光與半導體參數分析儀來完成。在30 keV加速電壓轟擊下，元件表面受到類似離子佈值而形成許多缺陷、空缺、甚至晶格錯位，因此元件在順偏壓1 V時，表面複合電流從10 pA上升至10 nA。
另外，透過電激發光光譜量測發現，無論在低溫或常溫量測下，當尺寸接近次微米尺寸之微小化元件，其發光波長峰值在高電流密度下，幾乎是定值。而在小電流下，微小型LED直接呈現紅移。會與傳統LED有這樣的差異性，推斷應該是內部應力受到微小化後釋放所致，而大電流下，則是熱效應(Joule Heating Effect)與能帶填充效應(Band-filling Effect)互相抵制而造成穩定波長。
最後，利用SRIM模擬軟體分析離子轟擊下氮化鎵材料內部缺陷分佈，並透過光譜量測到之黃光區域做定性探討，發現2.27 eV 與2.11 eV 兩個峰值恰巧對應到與鎵空缺相關受體能隙躍遷。從模擬分析得到在鎵離子轟擊下產生之鎵空缺數量約為氮空缺的1.5倍，因此推估FIB在轟擊時，對氮化鎵材料有明顯影響，了解缺陷產生對於利用FIB製備穿透式顯微鏡試片有很大的幫助。

Direct wide-bandgap gallium nitride (GaN) and other III-nitride based semiconductors have been used for modern lighting industry due to its capability of various indium compositions, which enables the wavelength covers from violet to near infrared. Light-emitting diodes (LEDs) have attracted considerable attention not only for the general lighting but also for back light units in display applications. Spontaneous polarization and piezoelectricity polarization in multi-quantum wells reduce the coupling efficiency of electrons and holes wavefunctions; and further, the high electrical power density enhancing the internal heating inside the LED causes the wavelength unstable, which limits the biomedical technology.
In this dissertation, focused ion beam (FIB) was used to prototype traditional LED into sub-micrometer scale. The cathodoluminescence (CL) of InGaN/GaN MQW nanopillars were investigated from previous research, but few researches focused on electrical and optical property under electric pumping. Single slice and rod LEDs were fabricated and measured successfully.
Temperature-dependent electroluminescence (EL) and property of current-voltage minimized LEDs were investigated. Recombination current increases after ion beam process. This result might come from implantation of 30 KeV accelerated Ga+, creating defect states, vacancies, and even crystal misfits. Nearly constant peak wavelength under high current density was observed in minimized LEDs, whiles redshift occurs at low current density. The redshift is due to strain release after ion beam milling, and nearly constant wavelength might origin from the competition between Joule heating effect and band-filling effect.
We use the stopping and range of ions in matter (SRIM) to simulate the projected ion range and distinguish the types of vacancies after FIB milling. There are two peaks locate on the yellow luminescence band in EL spectra, and the peak energies are related to optical transition of VGa. The result is consistent with the large number of VGa created during FIB process. This information of defect type is very important for TEM analyses.

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