在本論文中，我們將從事藍光ZnGa2O4螢光體應用於低壓場發射顯示器之研究。由於場發射顯示器的低工作電壓及高電流密度的需求，應用於場發射顯示器之發光層必須考慮其導電特性。因此，在本實驗裡發光層中螢光體適當的導電性增強是必要的。
在本實驗中，利用沉澱法將螢光體材料沉積在ITO玻璃基板上。針對FED螢光體低電阻特性的需求，我們將藍光ZnGa2O4螢光體分別混合不同比例的In2O3導電性粉末(0wt%~20wt%)，進一步發現In2O3的摻雜有助於螢光體亮度及導電度的提昇。由實驗結果得知，亮度隨著In2O3 摻雜比例而增加，最佳的摻雜量為12wt%，在此時，可達到最大亮度及最佳的導電度。當In2O3摻雜過量超過12wt%時，會使亮度有開始下降的趨勢。然而，混合導電粉末In2O3可以改善發光層的亮度、效率及穩定性是不可否認的。
在熱處理方面，利用高溫爐管進行熱處理，熱處理條件是固定在450℃恆溫維持一小時，並通入Ar氣體避免不必要的氧化。由實驗結果知道，經過熱處理之螢光體，可獲得較佳的亮度。
為使ZnGa2O4螢光體有更佳的結晶性及更佳的亮度表現，我們將原先1200℃反應製成的ZnGa2O4螢光體粉末進行二次燒結反應，二次燒結反應溫度分別以1000℃及1300℃作為實驗。由實驗結果知道，二次燒結反應在1300℃時，螢光體粉末可得到更佳的結晶性， 於是結晶性較佳的螢光體也會使亮度提昇。
在本實驗中，經過導電性增強及熱處理過後的ZnGa2O4螢光體其CIE彩色座標測得為X=0.1646、Y=0.1320。
*作者 **指導教授

In this dissertation, we devote ourselves to the study of low-voltage phosphor of ZnGa2O4 for the application of field emission display. In accordance with the requirement of low operation voltage and high current density for FED, the conductivity of phosphor layer is important. Therefore, it is necessary to enhance the conductivity of phosphor layer.
In this experiment, we use the method of sedimentation to deposit phosphor on ITO glass substrate. In view of the demand of low resistance of phosphor for FED, we add different weight percent of In2O3 (0wt% ~ 20wt%) to the blue ZnGa2O4 phosphor. However, we find that it is helpful to add In2O3 to ZnGa2O4 phosphor. The luminance and conductivity of phosphor layer are increased by mixing In2O3 with ZnGa2O4 phosphor. From the experimental results, the luminance and conductivity increase as the In2O3 percentage is increased. They reaches their maximum at 12wt% In2O3 and decrease at higher contents. But, it is not denying that adding conductive powders can improve the luminance and stability of phosphors and increase luminous efficiency.
The heat treatment is executed by using tubular furnace in the experiment. The conditions of heat treatment are 450℃ and lasting for 1 hour. Ar gas is introduced into the tubular furnace during heat treatment process in order to avoid needless oxidation. From the experimental results, we find that the better luminance performance is obtained after heat treatment.
In order to get better crystallization and luminous performance of ZnGa2O4 phosphor, secondary fired process for the ZnGa2O4 phosphor is executed. For the experimental comparison, the secondary fired temperature are 1000℃ and 1300℃, respectively. Finally, we find that the luminance and crystallization of ZnGa2O4 phosphor is improved after secondary fired process of 1300℃.
After heat treatment, the CIE chromaticity of the blue ZnGa2O4 phosphor layer with conductive treatment is measured. It can be observed that the color coordinates of blue ZnGa2O4 phosphor layer are X=0.1646, Y=0.1320.
*The author **The advisor

Content
Abstract (in Chinese)……………………………………………Ⅰ
Abstract (in English)…………………………………………… Ⅲ
Acknowledgement………………………………………………Ⅴ
Content…………………………………………………………Ⅵ
Table Captions…………………………………………………..Ⅸ
Figure Captions…………………………………………………Ⅹ
Chapter 1 Introduction………………………………… …1
1-1 The Development of Field Emission Device………………….3
1-2 Phosphor Layer……………………………………………..4
1-3 Aim of the Study……………………………………………5
1-4 Outline of the Dissertation……………………………… ….5
Chapter 2 Theory and Material Properties……………… ………7
2-1 Theory Background of Field Emission……………… ……..7
2-2 Phosphor Material Property…………………………… …...9
2-2-1 Host material…………………………………………...10
2-2-2 Luminescent center…………………………………….10
2-2-3 The optical property of ZnGa2O4: Mn phosphors…… ...11
2-3 Luminescent Efficiency……………………………………... 13
Chapter 3 Experimental Process and System Configuration……………….. 14
3-1 Experimental Process…………………………………………14
3-1-1 Substrate Preparation…………………………………...14
3-1-2 Fabrication of ZnGa2O4 Powder Phosphor……………..15
3-1-3 Fabrication Process of Phosphor Layer………………...16
3-1-4 Heat Treatment………………………………………… 17
3-2 Measurement System…………………………………………18
3-2-1 XRD Analysis…………………………………………..18
3-2-2 Energy dispersive spectrometer (EDX)………………...19
3-2-3 Photoluminescence (PL)………………………………..19
3-2-4 Cathodoluminescence (CL)……………………………. 20
3-2-5 UHV Luminance Measurement System………………..22
Chapter 4 Enhancement of Luminance and Conductivity…………………...23
4-1 ZnGa2O4 Powder Phosphor Added In2O3…………………… 23
4-1-1 The Process of Adding Conductive In2O3 Powders...….23
4-1-2 XRD Analysis of ZnGa2O4 Phosphor…………………. 24
4-1-3 EDS Analysis of ZnGa2O4 Phosphor………………….. 24
4-2 ZnGa2O4 phosphor deposited on ITO glass…………………. 24
4-2-1 XRD Analysis………………………………………….25
4-2-2 Photoluminescence Analysis…………………………..25
4-2-3 Luminance Analysis…………………………………...26
4-3 The Influence of In2O3 weight percent on the Conductivity
of ZnGa2O4 phosphor………………………………………...27
4-4 Heat Treatment Effect………………………………………. 28
4-5 Varying Mole Ratio of ZnO/Ga2O3 during Phosphor
Fabrication Process………………………………………….. 29
4-5-1 XRD Analysis………………………………………….29
4-5-2 Cathodoluminescence………………………………….29
Chapter 5 The Improvable Characteristics of ZnGa2O4 Powder Phosphor….31
5-1 XRD Analysis of ZnGa2O4 Phosphor obtained by
Secondary Fired Process……………………………………... 31
5-2 Luminance Analysis…………………………………………..32
5-3 Luminous Efficiency Analysis………………………………..33
Chapter 6 Conclusion……………………………………………………….. 35
References…………………………………………………………………...38
Autobiography
Copyright Authorization
Table Captions
Table 3-1 The main conditions of sedimentation
Table 4-1 The relation between In2O3 weight percent and resistivity of
ZnGa2O4 phosphor
Figure Captions
Fig. 1-1 Schematic plot of a field emission display (FED)
Fig. 2-1 ZnGa2O4 lattice
Fig. 3-1 The structure of tubular furnace
Fig. 3-2 Temperature profile for sintering
Fig. 3-3 The fabrication process for ZnGa2O4 phosphor
Fig. 3-4 Preparation process for phosphor layer
Fig. 3-5 The configuration of photoluminescence apparatus
Fig. 3-6 The schematic diagram of the photoluminescence apparatus
Fig. 3-7 Detector scheme of the cathodoluminescence apparatus
Fig. 3-8 Cathodoluminescence measurement system
Fig. 4-1 Fabrication process for the ZnGa2O4 phosphors mixed with In2O3
Fig. 4-2 The XRD pattern of ZnGa2O4 phosphor
Fig. 4-3 The XRD pattern of ZnGa2O4 added 12wt% In2O3
Fig. 4-4 The EDS analysis of fabricated ZnGa2O4 powder phosphor
Fig. 4-5 The SEM photographs of ZnGa2O4 obtained at fired temperature of
1200℃
Fig. 4-6 The SEM photographs of ZnGa2O4 phosphor deposited on ITO
glass substrate
Fig. 4-7 The XRD pattern of ZnGa2O4 deposited on ITO glass substrate
Fig. 4-8 Photoluminescence spectra of ZnGa2O4 phosphor with different
In2O3 weight percentage
Fig. 4-9 The luminance as a function of In2O3 weight percent and anode
current
Fig. 4-10 Luminance intensity of ZnGa2O4 with different mixing levels of
In2O3
Fig. 4-11 The luminance of ZnGa2O4 phosphor added 12wt% In2O3
Fig. 4-12 Luminance efficiency as a function of In2O3 weight percentage
and anode current
Fig. 4-13 The metrical method of determining ZnGa2O4 powder phosphor
resistivity
Fig. 4-14 The XRD diffraction pattern of the piece of ZnGa2O4 phosphor
after pressing process
Fig. 4-15 (a) The relation between resistivity and In2O3 weight percentage
when the applied voltage is 100 V
(b) The relation between conductivity and In2O3 weight percentage
when the applied voltage is 100 V
Fig. 4-16 The luminance variation of ZnGa2O4 phosphor screen versus
anode current
Fig. 4-17 The XRD patterns of phosphor with different composition ratio of
ZnO/Ga2O3
Fig. 4-18 Cathodoluminescence spectra of Zinc Gallate with different
ZnO/Ga2O3 mole ratio
Fig. 5-1 The XRD patterns of ZnGa2O4 powders obtained at different firing
temperature conditions (a) First firing: 1200℃, 5 hours (b) Second
firing: 1000℃, 5 hours (c) Second firing: 1300℃, 5 hours
Fig. 5-2 The XRD patterns of ZnGa2O4 phosphors deposited on ITO glass
(a) First firing: 1200℃, 5 hours (b) Second firing: 1000℃, 5 hours
(c) Second firing: 1300℃, 5 hours
Fig. 5-3 (a) and (b) SEM photographs of ZnGa2O4 powders obtained at
secondary fired temperature of 1000℃
(c) SEM photograph of ZnGa2O4 phosphor obtained at secondary
fired temperature of 1000℃and deposited on ITO glass
Fig. 5-4 (a) and (b) SEM photographs of ZnGa2O4 powders added 12wt%
In2O3 and obtained at secondary fired temperature of 1000℃
(c) The deposited situation of ZnGa2O4 phosphor which is added
with 12wt% In2O3 and obtained at secondary fired temperature
of 1000℃
Fig. 5-5 (a) Surface morphology of ZnGa2O4 powders obtained at secondary
fired temperature of 1300℃
(b) SEM photograph of a ZnGa2O4 grain
Fig. 5-6 Luminance as a function of In2O3 weight percent and anode current
(a) First firing: 1200℃, 5 hours (b) Second firing: 1000℃, 5 hours
(b) Second firing: 1300℃, 5 hours
Fig. 5-7 The Luminance of ZnGa2O4 phosphor for different mixing levels of
In2O3
Fig. 5-8 The luminescent efficiency variation versus anode current for
ZnGa2O4 phosphor screen added with 12wt% In2O3
Fig. 6-1 The CIE chromaticity of the blue ZnGa2O4 phosph

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