本篇文章介紹了由磁控式濺鍍系統生長氧化鉭（Ta2O5）薄膜於n型氮化鎵（GaN）或p型氮化鎵基材製作金屬－氧化層－半導體 (MOS)結構的元件，與由硬桿式共軛高分子（conjugated rigid-rod polymers）PBT成長於n型氮化鎵上製作金屬－絕緣層－半導體（MIS）結構的元件，且詳述其製作流程與結構。
在以GaN為基材的MOS/MIS結構電容－電壓（C-V）量測中，可觀察到阻滯（hysteresis）現象，且阻滯現象會隨著量測時掃瞄步距（scanning step）的延遲時間（delay time）改變而變化。這可能是由氧化層中的移動電荷（mobile charge）與接面間的陷阱電荷（interface trap charge）所造成的影響。基材GaN的載子濃度（carrier concentration）可由C-V量測的結果作運算，並將之與霍爾量測的結果作比較。此外平帶電壓（flatband voltage）與起始電壓（threshold voltage）亦經由計算與C-V的量測結果作比較。

In this study, metal-oxide-semiconductor (MOS) capacitances were prepared with rf magnetron sputtering of Ta2O5 on both n-type GaN and p-type GaN. And metal-insulator-semiconductor (MIS) capacitances were prepared with conjugated rigid-rod polymers PBT on n-type GaN. The processes of fabrication the diodes were shown, and the structures of MOS/MIS diodes were represented. Hysteresis was observed in high-frequency capacitance-voltage (C-V) measurements. And the hysteresis was changed with different scanning delay time on scanning step. They were ascribed to mobile charges and interface charges. The carrier concentration were calculated and compared with the Hall results. The flatband voltage and threshold voltage were calculated and compared with C-V curves which were measured.

CONTENTS


CHAPTER 1 INTRODUCTION
1-1 APPLICATION AND PROPERTIES OF GaN ……………………….…1
1-2 THE CONJUGATED RIGID-ROD POLYMER PBT……………………..2

CHAPTER 2 THEORY AND FORMULATION
2-1 THEORY OF C-V MEASUREMENT FOR MOS STRUCTURE……..3
2-1-1 MOS Structure
2-1-2 Oxide and Interface Trapped Charges, Oxide Integrity
2-1-3 Band-Bending Approximation
2-2 FORMULATIONS OF CALCULATING PARAMETERS OF MOS/MIS STRUCTURE………………………………………………………...…11

CHAPTER 3 EXPERIMENT
3-1 SPUTTERING OF Ta2O5 ON GaN FOR MOS STRUCTURE…………19
1. Samples Cleaning
2. Ohmic Contact
3. Photolithography
4. Sputtering Process
5. The measure of thickness
3-2 THE FABRICATION OF PBT/GaN MIS STRUCTURE..…………...…23
1. Samples Cleaning
2. Ohmic Contact
3. Spin-coated Process
4. Metal Contact
3-3 THE C-V MEASUREMENT SYSTEM……………………………...…25

CHAPTER 4 RESULTS AND DISCUSSION
4-1 THE C-V CURVE AND HYSTERESIS ANALYSIS OF Ta2O5 ON
n-GaN AND p-GaN.……………...………………………………..……26
4-1-1 n-type GaN-jk27N
4-1-2 p-type GaN-jk46P
4-2 THE C-V CURVE AND HYSTERESIS ANALYSIS OF PBT ON
n-GaN..………………………………………………………………......36
4-2-1 n-type GaN-jk27N
4-3 THE C-V CURVE VS. CARRIER CONCENTRATION ANALYSIS…...39
4-3-1-a PBT on GaN-jk17N and jk27N
4-3-1-b AlN on GaN-jk17N and jk27N
4-4 THE C-V CURVE AND ANALYSIS OF Ta2O5 ON p-GaN……………...40
4-4-1 Ta2O5 on GaN-jk18P

CHAPTER 5 CONCLUSION……………..………………………42

Reference………………………………………………………………….77

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