formation of air void on patterned sapphire substrate for high light extraction efficiency
- 주제(키워드) gallium nitride , patterned sapphire substrate , Metal-Organic Chemical Vapor Deposition
- 발행기관 고려대학교 대학원
- 지도교수 변동진
- 발행년도 2017
- 학위수여년월 2017. 8
- 학위구분 석사
- 학과 대학원 신소재공학과
- 원문페이지 76 p
- 실제URI http://www.dcollection.net/handler/korea/000000077240
- 본문언어 영어
- 제출원본 000045915343
초록/요약
Recently, the patterned sapphire substrate (PSS) method is being used in manufacturing industries because of the enhancement of the internal quantum efficiency (IQE) and the light extraction efficiency (LEE) by decreasing the threading dislocation density (TD) and improving photon scattering. However, air void structure in LEDs has been also studied as means to increase IQE and LEE for high efficiency optoelectronic device. Although most of LEDs with air void have been made using an additional crystallographic wet etching process, excessive wet etching process can result in epitaxial growth problem including surface pits and a rough surface. In this study, to improve the light extraction efficiency of light emitting diodes, we investigate a new method to build up air void on PSS to overcome issues by wet etching process. It is confirmed that GaN was grown on specific planes such as c, n, r-plane by the behavior of GaN growth as various process conditions. Based on the behavior of GaN growth by process conditions, air void can be fabricated by suppressing c-plane and growing on n-plane in PSS lens, using surface treatment by selective photoresist carbonization. These results were obtained from field emission scanning electron microscope (FE-SEM) that can show up the growth behavior of GaN and selective area electron diffraction (SAED) pattern of transmission electron microscopy (TEM) that can perform the analysis of crystallographic plane. To analyze the cause of selective growth on specific planes existed on PSS, contact angle measurement was implemented and the cause of growth suppression could be confirmed by the surface energy difference.
more목차
ABSTRACT I
LIST OF TABLES III
LIST OF FIGURES IV
Chapter Ⅰ : BACKGROUND OF RESEARCH - 1 -
1.1 Introduction to Ⅲ-nitrides growth - 1 -
1.2 Crystal structure and properties of Ⅲ-nitrides growth - 2 -
1.3 Patterned Sapphire substrate issues for Ⅲ-nitrides materials - 9 -
CHAPTER Ⅱ : GROWTH SYSTEM AND MATERIAL CHARACTERIZATION METHODOLOGY - 10 -
2.1 Overview of reaction processes in MOCVD growth - 11 -
2.2 Overview of the home-made MOCVD system - 15 -
2.3 Material characterization methodology - 20 -
Chapter Ⅲ: THE FORMATION OF AIR VOID ON PATTERNED SAPPHIRE SUBSTRATE FOR HIGH LIGHT EXTRACTION EFFICIENCY - 25 -
3.1 Introduction - 25 -
3.2 Experimental details - 26 -
3.3 Result and Discussion - 30 -
Ⅳ. CONCLUSION - 60 -
Ⅴ. REFERENCES - 61 -
