寬能隙半導體材料氮化鎵具有優異的物理特性，適合高功率領域之材料應用。離子照射終端結構的步驟，可使元件之崩潰電壓大幅增加，為氮化鎵功率元件之重要製程。然而，高劑量的離子照射，伴隨著嚴重的輻射損傷效應，導致氮化鎵材料特性以及晶格中載子傳導機制，產生劣化的現象，為離子照射於終端結構應用須衡量之要點。本研究於氮化鎵材料進行氬離子、氦離子照射實驗，接續進行多項材料特性分析：透過霍爾效應量測與拉曼散射光譜分析，呈現受輻照氮化鎵之載子移除效應，經過180 keV、 6×1015 cm-2 氬離子照射之樣品，載子移除比例約為32.5 %；而離子照射所導致氮化鎵之載子傳輸機制劣化的情形，則反映在樣品薄膜電阻及載子遷移率的變化。透過X光繞射分析與拉曼散射光譜分析，定義樣品受輻照損傷的程度，並且判斷非晶層的形成，發生於180 keV、1.2×1015至3.6×1015 cm-2劑量範圍的氬離子照射；而拉曼光譜結果則呈現氮化鎵次晶格的劣化情形。光致發光頻譜之分析結果，呈現氮化鎵輻照誘發缺陷對載子復合行為的影響，導致近能帶邊緣放射以及黃光帶雜質輻射躍遷，均出現相應的特性變化。氮化鎵在氬離子照射後所產生的能隙減小、穿透率下降等變化，則透過紫外-可見光譜取得分析結果。此外，退火程序對氮化鎵形成的溫度效應，以及背後的機制於本論文中亦有探討。在低溫範圍，退火之溫度效應由氮化鎵內的輻照誘發缺陷特性變化所主導；而較高的溫度下，退火程序則產生顯著的氮化鎵晶格修復效應，使氮化鎵材料特性呈穩定的回復。上述的材料分析結果經過統整比對，使本論文得以就材料科學領域，分析離子照射實驗於氮化鎵材料所產生之損傷效應，作為終端結構製程上的參考。

Gallium nitride (GaN) -based electronic devices possess great potential in applications of power electronics due to its wide bandgap and other excellent intrinsic properties. To suppress the crowded electric-field and thus increase the breakdown voltage of GaN power devices during reverse operation, edge termination technique should be incorporated. Heavy ion implantation creates radiation-induced defects that modify the electric-field distribution in GaN and thus achieve edge termination in n-type GaN. However, ion irradiation with high fluence inevitably causes radiation damage, which is detrimental to the electrical and material properties of GaN crystal. In this study, argon (Ar) irradiation and helium (He) irradiation was performed on epitaxial GaN layer. The radiation effects of ion implantation on the characteristics of GaN epitaxial layer were then thoroughly investigated. Hall effect measurement results indicated that the carrier concentration of GaN decrease with the increase of Ar ion fluence. About 32.5% carriers in GaN were removed after Ar ion implantation with a maximum fluence of 6×1015 cm-2. Furthermore, the degradation on carrier transportation in GaN lattice is also presented. As found in XRD spectra, a localized amorphous layer may be formed in GaN crystal when Ar ion fluence is at the range of 1.2×1015 to 3.6×1015 cm-2. The results of Raman scattering spectra also evidenced that Ar ion implantation on GaN leads to the formation of sublattice damage and degradation in electrical properties. From the PL spectra results, the radiation-induced defects are found to be trapping carriers effectively, causing the decay of near band edge emission (NBE) and yellow luminescence band (YL band). The reduction of bandgap energy and decreased transmittance of GaN after argon ion irradiation are also analyzed through ultraviolet-visible (UV-Vis) spectroscopy. In addition, post irradiation annealing was carried out. At a relatively low annealing temperature, the material characteristics of GaN is dominated by the behaviors of radiation-induced defects; at high annealing temperature, GaN recovers from radiation damage, leading to a remarkable restoration on its material characteristics. By comparing the results of above material analysis, this thesis offers valuable insights into the radiation damage effects of GaN caused by heavy ion irradiation, and can be serve as a reference for the heavy ion implantation edge termination on GaN device.

摘要........ i
Abstract........ ii
致謝........ iv
目錄........ v
表目錄........ vii
圖目錄........ ix
第一章 前言........ 1
第二章 文獻回顧........ 2
2.1 離子照射於終端結構應用........ 2
2.2 氮化鎵材料受粒子照射損傷研究........ 5
2.2-1 材料電性研究........ 5
2.2-2 材料結構性研究........ 8
2.2-3 輻照誘發缺陷之特性研究........ 11
2.2-4 光譜學研究........ 13
第三章 實驗方法........ 23
3.1 材料製備........ 23
3.2 SRIM 模擬........ 23
3.3 離子照射........ 24
3.4 退火步驟........ 26
3.5 材料分析........ 28
3.5-1 霍爾效應量測........ 28
3.5-2 X 光繞射分析........ 31
3.5-3 光致發光頻譜分析........ 33
3.5-4 拉曼散射光譜分析........ 35
3.5-5 紫外-可見光譜分析........ 37
第四章 結果與討論........ 38
4.1 SRIM 模擬........ 38
4.2 霍爾效應量測........ 40
4.3 X 光繞射分析........ 51
4.4 光致發光頻譜分析........ 56
4.5 拉曼散射光譜分析........ 63
4.6 紫外-可見光譜分析........ 70
第五章 結論與未來建議........ 72
5.1 結論........ 72
5.2 未來建議........ 73
文獻參考........ 75

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