本論文是在探討如何利用超音波霧化熱裂解沉積法製備非晶氧化銦鎵鋅薄膜光電晶體。為了減少製程時間且降低成本，我們選用了比溶膠凝膠法更易控制薄膜厚度的非真空製程 – 超音波霧化熱裂解沉積法。我們將此製程應用於薄膜電晶體之通道以及氧化層材料上，成功做出底閘極結構的薄膜光電晶體。
為了瞭解利用超音波霧化熱烈解沉積法製備的氧化銦鎵鋅薄膜晶像、表面粗糙度、晶粒大小、化學組成、氧空缺、折射係數、薄膜厚度，在本研究中我們利用以下技術來分析材料特性 (一) X-射線繞射分析、(二) 原子力顯微鏡、(三) 掃描式電子顯微鏡、(四) 化學分析影像能譜儀、(五) 橢圓偏光儀、(六) 穿透式電子顯微鏡。
在瞭解薄膜的材料特性後，我們將超音波噴霧熱裂解沉積技術應用於底閘極結構的薄膜光電晶體上，分別以440oC和430oC成長氧化鋁介電層和氧化銦鎵鋅主動層，並利用電流-電壓特性來確認元件的電性表現。
為了瞭解非晶氧化銦鎵鋅薄膜光電晶體之光響應，我們給予入射波長為260nm到450nm的光，再利用光電流與暗電流去計算出在不同波段下元件的光響應程度，並分析此非晶氧化銦鎵鋅薄膜之截止波段，推算出薄膜的能隙寬。在本研究中，超音波噴霧熱裂解沉積法對於未來以低成本和低製程時間開發非晶氧化銦鎵鋅薄膜光電晶體有很大的幫助。

In this thesis, we will investigate how to fabricate amorphous InGaZnO thin film phototransistors by using ultrasonic spray pyrolysis deposition technique. In order to shorten the process time and reduce the cost, we use a much better non-vacuum process than sol-gel, ultrasonic spray pyrolysis deposition (USPD). USPD performs better ability on accurately controlling the thickness of the thin film. Applying this process to the active layer and the gate dielectric layer of the thin film phototransistor, we successfully fabricate the bottom-gate structure thin film phototransistor.
In order to understand the crystal, surface roughness, grain size, chemical composition, oxygen vacancy, refractive index and thickness of the IGZO thin film prepared by USPD, we used the following technique to analyze in this work. (1) X-ray Diffraction (XRD) (2) Atomic Force Microscopy (AFM) (3) Scanning Electron Microscope (SEM) (4) Electron Spectroscopy for Chemical Analysis (ESCA) (5) Ellipsometry (6) Transmission Electron Microscopy (TEM).
After understanding the material properties of the thin film, we applied the USPD technique to the bottom-gate structure thin film phototransistor and fabricate the Al2O3 gate dielectric layer and IGZO active layer at 440oC and 430oC, respectively. Furthermore, the current-voltage characteristics were measured.
In order to understand the spectra response of a-IGZO thin film phototransistor, we measured the photocurrent of the device under illumination with the range of measuring wavelength from visible region (450nm) to UV region (260nm) and calculate the responsivity. Besides, we can also calculate the bandgap of IGZO thin film from the cutoff wavelength (310nm). In this study, the USPD technique is helpful for the future development of a-IGZO thin film phototransistor with low cost and low process time.

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