本篇論文主要探討利用後退火製程改善過氧化氫（雙氧水）氮化鋁鎵/氮化鎵高電子遷移率電晶體之氧化層品質，雙氧水具有很強的氧化能力，可以氧化氮化鋁鎵表面，以形成氧化層。接著利用後退火方式在不同氣體、溫度、時間來提昇氧化層品質。
為了瞭解原生氧化層的（一）表面粗糙度、（二）化學組成、（三）薄膜的厚度與（四）鈍化層薄膜對二維電子雲的影響，因此在研究中使用了（ㄧ）穿透電子顯微鏡、（二）X光繞射儀、（三）化學分析電子儀與（四）原子力顯微鏡（五）霍爾量測。在穿透電子顯微鏡薄膜量測中，發現到使用了後退火製程，薄膜的厚度會有所下降，其中雙氧水處理、後退火製程氧400°C 10分鐘以及氮氣400°C 20分鐘薄膜厚度分別為13.33 nm、11.11 nm、9.51 nm。在X光繞射儀分析中，觀察氧氣在400°C 15分鐘以及氮氣400°C 25分鐘會有結晶態情形。在化學分析電子儀中的半定量分析瞭解到氧化層的材料主要為氧化鋁。在原子力顯微鏡觀察中，比較未經過雙氧水處理、雙氧水處理七分三十秒、後退火製程氧氣400°C 10分鐘、與氮氣400°C 20分鐘表面粗糙度分別為: 1.90 nm、1.53 nm、0.95 nm、0.90nm。在霍爾量測中，比較經過雙氧水處理以及氧氣、氮氣的後退火製程，發現片電子濃度有些許下降而電子遷移率有所上升。除此之外，我們也利用遲滯效應與表面狀態密度判定後退火製程所能降低表面缺陷之幅度。
在瞭解薄膜之材料分析後，進一步將後退火製程應用於金氧半高電子遷移率電晶體之上。首先，利用比較不同氣體、溫度、時間找出最佳的元件特性，我們同時也發現在氧氣400°C 10分鐘、氮氣400°C 20分鐘有最好的特性改善。因此，在接下來的直流電性與微波電性比較，採用未經雙氧水處理、雙氧水處理、後退火氧氣400°C 10分鐘、與氮氣400°C 20分鐘做為比較。而在變溫量測中發現後退火製程之後的元件有較佳的熱穩定性。為瞭解元件在高頻應用的狀況，而進行微波特性的量測，發現在截止頻率、最大震盪頻率、與線性度上皆有改善。在功率表現上，無論是在2.4GHz或5.8GHz的狀況下，經由後退火製程技術皆能提升功率特性的表現。在電流崩潰的表現上，發現利用後退火製程之元件能夠有效改善電流崩潰之效應。無論是在高頻雜訊或是在低頻雜訊的部分，元件經過後退火製程後可明顯改善雜訊強度。這種利用後退火製程方式能夠有效提升氮化鎵高電子遷移率電晶體的特性，並使其應用更加廣泛。

The research is mainly investigated on the improvement of hydrogen peroxide (H2O2) Metal-Oxide-Semiconductor high electron mobility transistor by using post oxide annealing (POA). Hydrogen peroxide has a strong oxidation capability, it can oxidize the surface of AlGaN to form the surface oxide layer. After that, we use different ambiences, temperatures, time to improve the quality of oxide layer.
In order to know (1) surface roughness, (2) chemical composition, (3) oxide thickness, and (4) passivation layer effect on two-dimensional electron gas concentration (2DEG) of oxide layer, the (1) Transmission Electron Microscopy (TEM) (2) X-ray Thin-film Diffraction (XRD) (3) Electron Spectroscopy for Chemical Analysis (ESCA) (4) Atomic Force Microscopy (AFM), and (5) Hall Measurement were required to use in the research. From TEM, we observe that the thickness of oxide layer which with post-oxide annealing would reduce. The oxide thickness of H2O2 treatment, POA with O2 400°C 10minutes, and N2 400°C 20minutes are 13.33 nm, 11.11 nm, 9.51 nm, respectively. From the XRD analysis, there are crystallization at the POA with O2 400°C 15 minutes, and N2 400°C 25 minutes. From ESCA, the results of the semi-quantitative analysis show the oxide layer is aluminum oxide. The observation of AFM compare without H2O2 treatment with H2O2 treatment 7 minutes 30seconds, POA with O2 400°C 10 minutes, and N2 400°C 20 minutes. Their surface roughnesses were 1.90 nm, 1.53 nm, 0.95 nm, and 0.90 nm, respectively. The Hall measurement was compared with H2O2 treatment 7 minutes 30seconds, POA with O2 and N2 ambiences, the sheet concentration was slightly reduced and the electron mobility would improve. In addition, the reduced oxide layer traps were confirmed by utilizing the hysteresis and interface state density.
After material analysis, the POA was applied to the fabrication of high electron mobility transistors. First, compared the different gases, temperatures, and time, we found that there were the optimal characteristics when POA with O2 400°C 10 minutes, and N2 400°C 20 minutes. Hence, the following texts will demonstrate comparisons of DC and RF characteristics of devices by using without H2O2 treatment, with H2O2 treatment, POA with O2 400°C 10 minutes, and N2 400°C 20 minutes. During the temperature–dependent characteristics measurement, the devices with POA have better thermal stability were observed.
In order to know the condition of devices operated under high frequency, microwave characteristics measurement is required. We noticed that cutoff frequency, maximum oscillation frequency, and linearity would be improved. Power characteristics demonstrated the device characteristics at 2.4GHz and 5.8GHz would be improved by using POA. The reduced current collapse was observed by using POA. No matter at the high frequency noise or low frequency noise, the observation of device characteristics would improve the noise level.
The post-oxide annealing can effectively improve the characteristics of GaN HEMTs and make its applications more comprehensive.

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