以氮化鎵為基底的材料已成功應用於短波長雷射二極體，發光二極體及紫外光光檢測器。在本實驗中，我們已成功的使用有機金屬氣相沈積法把氮化鎵磊晶膜生長在三氧化二鋁基板上。並對生長氮化鎵磊晶膜前之基板氮化溫度和氮化鎵緩衝層之生長溫度與生長時間並氮化鎵磊晶膜的生長溫度等參數進行研究。根據77K的光激發光譜、X光散射測量、掃瞄式電子顯微鏡的結果，瞭解氮化鎵的基本特性，並利用上述方式，生長更好的氮化鎵磊晶膜。在本實驗中，發現緩衝層在升高溫時會有再結晶的現象，此現象亦成為影響單晶品質及表面平整度的重要參數。根據實驗的結果，我們針對黃光區及施體受體對的成因做了深入的研究及探討。

The materials based on GaN have successfully developed on short-wavelength laser diodes (LDs), light-emitting diodes (LEDs) and ultraviolet photodetector. In this study, GaN epitaxial layers have been successfully grown on sapphire substrates. We used several methods including the nitridation temperature for substrates before growing epilayer, the growth temperature and time of buffer layer and the growth temperature of GaN epilayer to study it. From the results of the photoluminescence (PL) measured at 77K, the X-Ray diffraction measurement, SEM cross sectional views to realize the characteristic and we get a better qualities of GaN epilayers after using the foregoing methods. In this study, the re-crystallization of the buffer layer would occur while temperature re-rise to high temperature, and the phenomenon of conglomeration influence the quality and morphology of GaN epilayers. According to the results of the experiments, we study the mechanisms of yellows luminescence and donor-acceptor pair.

CONTENTS........................................I
LIST OF FIGURES...............................III
ABSTRACT........................................V

1.INTRODUCTION..................................1
1.1 Developments and Applications of Short
Wavelength Light Emitting Diode.............1
1.2 Materials for Blue LEDs.....................3
1.2.1 SiC Blue LEDs.............................3
1.2.2 ZnSe Blue LEDs............................4
1.2.3 GaN Blue LEDs.............................5
1.3 Developments of Short Wavelength Light
Emitting Diode Based on III-V Nitride
Materials...................................7
1.4 Group-III Nitride Compund Semiconductors....9

2.EXPERIMENTS..................................14
2.1 MOCVD Growth System........................14
2.1.1 Flexibility, Simplicity and Versatility..14
2.1.2 Halide Free..............................15
2.1.3 Single Hot Zone and Cold Wall System.....15
2.1.4 Capability of Multiple Heterostructure...16
2.1.5 High Temperature and Low Pressure........16
2.2 Growth System Design.......................17
2.2.1 Equipment Apparatus......................17
2.2.2 Gas Handling System......................17
2.2.3 Reaction Chamber Design..................18
2.2.4 Heating System...........................19
2.2.5 Exhaust System...........................19
2.2.6 Safety Equipment Considerations..........19
2.3 Substrate Preparation......................20
2.4 Growth Processes...........................21
2.5 Evaluation of GaN Epilayers................22

3.RESULTS AND DISCUSSION.......................24
3.1 Optical Properties.........................24
3.2 Effect of Baking...........................26
3.2.1 PL Properties............................26
3.2.2 X-Ray Measurements.......................26
3.3 Effect of the Flow rate of Ammonia.........28
3.3.1 PL Properties............................28
3.3.2 X-Ray Measurements.......................29
3.3.3 SEM Analysis.............................29
3.4 Effect of the Flow Rate of TEGa............30
3.4.1 PL Properties............................30
3.4.2 X-Ray Measurements.......................30
3.4.3 SEM Analysis.............................31
3.5 Effect of the Temperature of Nitridation
and Buffer Layer...........................32
3.5.1 PL Properties............................33
3.5.2 X-Ray Measurements.......................35
3.5.3 SEM Analysis.............................35
3.6 Effect of the Growth Time of Nitridation...37
3.6.1 PL Properties............................37
3.6.2 X-Ray Measurements.......................37
3.6.3 SEM Analysis.............................37
3.7 Effect of the Growth Time of Buffer Layer..38
3.7.1 PL Properties............................39
3.7.2 X-Ray Measurements.......................39
3.8 Effect of the Growth Temperature of GaN
Epilayer...................................40
3.8.1 PL Properties............................40
3.8.2 X-Ray Measurements.......................40
3.9 Recrystalliztion of Buffer layer...........41
3.10 Other Analyses............................42
3.10.1 X-Ray Measurements......................42
3.10.2 AES Analysis............................42
3.10.3 FTIR Analysis...........................43
3.10.4 AFM Analysis............................43
3.11 Mechanism of DAP in Our Experiments.......44
3.12 Mechanism of Yellow Luminescence..........45


4.CONCLUSIONS..................................48

REFERENCE......................................74

REFERENCE
[1] J. Nishizawa, F. Sakurai, Y. Okuno, and K. Itoh,