研究生: |
張運旋 Yun-hsuan Chang |
---|---|
論文名稱: |
p型氮化鎵成長過程中添加三氯化鎵作為氫自由基捕捉劑之研究 Growth of p-GaN film by adding gallium trichloride as H scavenger in MOCVD system |
指導教授: |
洪儒生
Lu-Sheng Hong |
口試委員: |
黃鶯聲
Ying-Sheng Huang 陳隆建 Lung-Chien Chen 黃振斌 jenn-bin Huang |
學位類別: |
碩士 Master |
系所名稱: |
工程學院 - 化學工程系 Department of Chemical Engineering |
論文出版年: | 2007 |
畢業學年度: | 95 |
語文別: | 中文 |
論文頁數: | 122 |
中文關鍵詞: | p型氮化鎵 、電洞濃度 、電阻率 、電洞遷移率 、三氯化鎵 |
外文關鍵詞: | p-GaN, hole concentration, resistivity, mobility, gallium trichloride |
相關次數: | 點閱:370 下載:1 |
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本實驗是先分別於三種氣氛下以TMGa/Cp2Mg/NH3之MOCVD系統成長p型氮化鎵薄膜。首先,在全氮氣氣氛下成長時,發現成長壓力為75 torr時,可以成長出表面較為平坦的薄膜,但因薄膜電性仍未達到一般p型氮化鎵薄膜水準,所以嘗試改以氫氣作為原料載氣,來降低在全氮氣氣氛下成長時因雜質所造成的自我補償效應。於氫氣作為原料載氣氣氛下成長p型氮化鎵薄膜的過程中,需將薄膜成長溫度提高到1000 ℃才可獲得表面無六角形缺陷的p型氮化鎵薄膜,但因薄膜電阻率仍高達3.5 Ω-cm,所以考慮在全氫氣氣氛下成長p型氮化鎵薄膜。由實驗結果發現在全氫氣氣氛下成長p型氮化鎵薄膜時,必須再提高薄膜成長溫度到1030 ℃及增加Ⅴ/ Ⅲ族比至3758,才能避免薄膜表面形成六角形的缺陷。而經由電性量測發現,薄膜的電阻率的確可以降低至2.82 Ω-cm。最後利用添加三氯化鎵成長p型氮化鎵薄膜,發現於全氫氣氣氛下、[GaCl3]/[TMGa]分壓比為0.2時可成長出表面平坦及不需經後加熱處理即可得到電洞濃度2 × 1016 cm-3、電阻率13.2 Ω-cm及薄膜電洞遷移率為18.9 cm2/V-s的p型氮化鎵薄膜。而將此電性數據與之前我們在全氫氣氣氛下成長但未經過後加熱處理的p型氮化鎵薄膜電性相比 (載子濃度背景值為2 × 1016 cm-3)確實十分接近,由於我們添加GaCl3來成長p型氮化鎵薄膜時會蝕刻薄膜,若薄膜過薄時可能會導致電性量測不準,故所量測出來的數據仍需確認。未來將以厚度大於1μm的p-GaN的厚膜成長來評估GaCl3的添加效果。
p-GaN thin films were grown in three different ambient gases using TMGa, Cp2Mg and NH3 as Ga, Mg and N source, respectively. First, in H2 free ambient and growth pressure of 75 torr, p-GaN thin films had smoother surface, but the electrical properties film couldn’t use for LED device application. Second, for reducing self-compensating effect, H2 was used as carrier gas. The growth temperature had to be increased to 1000 ℃ to avoid trapezoidal defect forming on the film surface. After post annealing treatment, the resistivity of the thin film was still too high (3.5 Ω-cm). Third, when the film was grown at temperature of 1030 ℃, and Ⅴ/ Ⅲ ratio of 3758 in all H2 ambient, there was no trapezoidal defect forming on the surface. The resistivity could be reduced to 2.82 Ω-cm after post annealing treatment. Finally, p-GaN thin films were grown by adding GaCl3 in all H2 ambient. When [GaCl3]/[TMGa] ratio of 0.2 , it was obtained the hole concentration、resistivity and mobility was 2 × 1016 cm-3、13.2 Ω-cm and 18.9 cm2/V-s, respectively. However, the hole concentration was closed to background value (2 × 1016 cm-3). This value have to be checked by measuring thicker film (1μm).
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