(A) study of GaN single crystal growth and wafering method for high power LED = 고출력 LED를 위한 bulk GaN 단결정 성장 및

다국어 초록 (Multilingual Abstract)

GaN single crystal were grown on the vertical and horizontal reactors by the hydride vapour phase epitaxy (HVPE). The structural and optical characteristics of the GaN single crystal were investigated depending on the reactor type. The threading dislocations were observed starting from the GaN/sapphire interface and propagating within the GaN layer. In case of horizontal HVPE grown GaN were these dislocations were penetrate to the surface. however, vertical HVPE grown GaN were these dislocations were merge together. Etch pit density of two kinds of the GaN films were calculated to be approximately l.4 x 107 and l.2 x 106 cm_2 for GaN layers grown on horizontal and vertical reactors, respectively. double crystal x-ray rocking curve of the (0002) diffraction of the GaN film is found to have a full width at half maximum (FWHM) of 262 and 187 acrsec respectively. The variation of PL spectra and intensity are observed band edge transition at 3.39 eV. It is recognized that GaN grown in the vertical reactor showed a higher PL intensity. In addition, defect related YL bands are seen.
3 mm thickness grown by hydride vapor phase epitaxy and cut using a wire saw to produce freestanding wafers. These wafers then were, mechanically polished with diamond slurry and followed with chemical mechanical polishing for final surface preparation. Surface morphology were examined before and after thermal annealing process performed at 700, 800, 900, and 1000 °C for one hour, in air. Wafers with optimum surface quality submitted to thermal annealing treatment at 900°C were,
characterized by reduced scratched density and residual stress, and surface roughness of 0.096 nm. Surface quality improvement was confirmed by relatively large recovering of the room temperature near band edge luminescence intensity.

목차 (Table of Contents)

• Contents
• Abstract ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ---------------------------------------------3
• Chapter 1. Literature Review
• 1.1. The overview of wide-bandgap semiconductor ­­­­­­­­­­­­­-----5
• 1.2. Historical view of GaN and related materials-------­­­­­­­­­­­­­­­­­­­­­­­­17
• 1.3. Properties of Gallium nitride ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­----------------------25
• 1.3.1. Specific structure ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-----------------------------25
• 1.3.2. Chemical properties of GaN ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-------------------26
• 1.3.3. Thermal and mechanical properties of GaN­­­­­­­­­­­­­­­­­­­­­­­­­­­-----28
• 1.3.4. Electrical properties of GaN­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------------30
• 1.3.5. Optical properties of GaN­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­----------------------30
• 1.4. Key Drivers For Bulk GaN substrate commercialization success --------------------------------------------­­­­-32
• 1.4.1 Lasers and LEDs­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-------------------------------35
• 1.4.2 Power Switches ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------------------------36
• 1.4.3 High Frequency, High Power HEMTs­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-------------37
• 1.5. Bulk GaN Substrate Trends ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-----------------------38
• 1.5.1 Hydride Vapor Phase Epitaxy ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-------------------39
• 1.5.2 Ammonothermal Growth-------------------------­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­40
• 1.5.3 Solution Growth­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­---------------------------------41
• 1.5.4 Combined Growth Techniques-------------------­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­42
• 1.6 Summary­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­------------------------------------------44
• 1.7 The Purposes of This Study ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­------------------------44
• 1.8 Reference ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-----------------------------------------45
• Chapter 2. Characterization of GaN thick layer grown by HVPE : comparison of horizontal with vertical growth
• 2.1.Introduction--------------------------------------- ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­57
• 2.2. Experimental -------------------------------------­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­58
• 2.3. Result and discussion ----------------------------59
• 2.4. Conclusion ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­---------------------------------------66
• 2.5. Reference ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­----------------------------------------67
• Chapter 3. Structural and optical studies of thick freestanding GaN films deposited by hydride vapor phase epitaxy
• 3.1. Introduction ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------------------------------68
• 3.2. Growth and experimental technique ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­---------------69
• 3.3. Experimental results and discussion ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------72
• 3.4. Conclusion­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­---------------------------------------82
• 3.5. Reference­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­----------------------------------------83
• Chapter 4. Surface morphology and optical property of thermally annealed GaN single crystal substrate
• 4.1. Introduction -------------------------------------­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--­86
• 4.2. Experimental­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------------------------------87
• 4.3. Result and discussion­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-----------------------------89
• 4.4. Conclusion ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­---------------------------------------98
• 4.5. Reference ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­----------------------------------------98
• Chapter 5. Conclusion ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­-------------------------------100­
• Figure Caption ­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­--------------------------------------102
• Acknowledgement­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­­ ----------------------------------105