在這篇論文?堙A我們使用熱蒸鍍的方法鍍上不同的金屬
在不同的氮化鎵上來形成歐姆接觸，並且使用傳輸線模
型(TLM model)來量測其接觸電阻。我們使用面罩在氮
化鎵四個角落鍍上歐姆接觸，並且利用這四個歐姆接觸
來做霍爾量測。從霍爾量測的數據顯示，濃度越高的樣
品其接觸電阻較濃度低的樣品來得小。在這篇論文?堣]
展示了p 型氮化鎵在不同熱退火處理下對光致螢光光譜
的影響，而且p型氮鎵的載子濃度亦隨著不同的熱退火處
理而有所改變。
電容－電壓( C-V )的分析方法在求元件參數時，是
一個很有用的技術。在這篇論文?堙A我們展示了求MOS結
構參數的完整公式，並且使用砷化鎵MOS結構來做計算的
樣品。從Ta2O5/n-GaN MOS結構的高頻電容－電壓曲線，
揭露了用Ta2O5做為絕緣層材料和用GaN做為基材來做金氧
半場效電晶體(MOSFET)的可能性。我們會選Ta2O5做為絕
緣層材料，是因為Ta2O5是一種高介電常數的材料.

In this thesis we reveal that the Ohmic contacts
of n-type and p-type GaN are obtained by the
method of thermal evaporation. For different
types of GaN, different metals are used to
evaporate on GaN surface to form Ohmic contact.
The measurements of specific contact resistivity
were performed by TLM (transmission line model)
for different types of GaN. Also, we use a shadow
mask to form four Ohmic contacts on four corners
of GaN surface , and utilize the four contacts to
perform Hall measurement by Van der Pauw method.
By the data of Hall measurement, it indicates
that the specific contact resistivity of heavily
doped samples are smaller than lightly doped
samples. The effect of intensity photoluminescence
( PL ) spectrum of different annealing treatment
of p-type GaN are also demonstrated in this thesis.
And the carrier concentration of p-type GaN will
change with different annealing condition.
The method of C-V analysis is a powerful
technique to determine the parameters of device.
In this thesis, we exhibit completed formulation
of how to calculate all the parameters of MOS
structure, using Ga2O3/p-GaAs MOS structure as
calculated sample. The high frequency C-V curve
of Ta2O5/n-GaN MOS structure reveals a possibility
for fabricating a MOSFET using Ta2O5 as insulated
layer and GaN as substrate. In this thesis, we
utilize Ta2O5 as insulated material, because
Ta2O5 is a material with high dielectric constan.

CHAPTER 1 Introduction
1.1 Applications and Properties of GaN ....5
1-2 Thermal Evaporation ....6
1-3 Photoluminescence ....8
CHAPTER 2 Theory and Formulation
2.1 The Formation of Ohmic Contacts to Wide
Bandgap Semiconductor ....10
2.2 Contact Resistance ....17
2.3 Formulation of Calculating Parameters of
MOS Structure (Using Ga2O3/p-GaAs as
Calculated Sample) ....24
CHAPTER 3 EXPERIMENT
3.1 Samples Cleaning ....38
3.2 Evaporation Process ....39
3.3 Photoluminescence (PL) Measurement ....45
3.4 Hall Measurement ....46
3.5 Sputtering Process ....48
3.6 Samples Fabrication ....50
3.7 C-V Measurement ....53
CHAPTER 4 Results and Discussions
4.1 Hall Measurement ....55
4.2 Ohmic Contact for n-type GaN ....60
4.3 Ohmic contact for p-type GaN ....63
4.4 The Effects of Different Gas Annealing
of p-GaN ....68
4.5 Specific Contact Resistance ....72
4.6 C-V Analysis of Ta2O5/n-GaN ....77

CHAPTER 5 CONCLUSION
5.1 About the Achievement ....93
5.2 About the Challenge and Future Work....94
REFERENCE ....95

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