Synchrotron X-선 Reflectometry와 Atomic Force Microscopy를 이용한 SnO_(2)/Al_(2)O_(3)계의 표면 및 계면 분석 = Surface and interface analysis of SnO_(2)/Al_(2)O_(3) system using synchrotron X-ray reflectometry and atomic force microscopy

다국어 초록 (Multilingual Abstract)

Up to date, many scientists have studied the electrical and chemical properties of SnO₂ film as gas sensors and transparent optical electrodes. But there is less of the information for the epitaxial growth and surface growth dynamics of SnO₂ film.
Epitaxial growth of SnO₂ film is of both practical and fundamental interest.
Our study focused on surface growth and grain growth in SnO₂ thin film on sapphire(0001).
At 600℃, SnO₂ thin film is grown epitaxially along out-of-plane direction on sapphire by RF magnetron sputtering method. It has three variants structure, which makes dislocations and mosaics on surface and thus many grains in the SnO₂ film. The interface relation between SnO₂ film and sapphire has the ratio of 4/6 for epitaxial growth by extended atomic distance mismatch(EADM) theory.
During growth without a variation of lattice parameter along out-of-plane direction, many grains are formed along in-plane direction of thin film. As increasing of the film thickness linearly propotional to deposition time, the grain growth reveals crossover behavior of from scaling regime, which the grain size in out-of-plane direction increases according to power law at short length scale, to saturation regime which the grain size is saturated at long length scale. This saturation is due to limitation of grain growth by dislocations which are produced in order to dissolve the strain by thermal energy in SnO₂ film.
And our model for grain growth of SnO₂ film on sapphire is suggested.
For the study of surface growth dynamics, we analyze the surface roughness and height correlation functiono of SnO₂ film calculated from synchrotron x-ray reflectivity and atomic force microscopy(AFM) images. The in-situ measurements of x-ray reflectivity were performed in 3C2 beam line of Pohang light source(PLS) with our home-made sputtering system.
As increasing of the film thickness linearly propotional to deposition time, we find the scaling relation in surface roughness of SnO₂ film grown at room temperature and anormal behavior at 600℃. The growth exponent β given by the scaling relation is equal to 0.54±0.01 in sample grown at room temperature. And the height correlation functions calculated from AFM data of the last in-situ sample grown at room temperature and 600℃ show increasing of power law with lateral scan size. From these results roughness exponent α is given as approximately unity for the sample at room temperature and 600℃. Our results is compared with recent theoretical results for analysis of the surface growth dynamics of SnO₂ film.

목차 (Table of Contents)

• 목차
• 목차 = ⅰ
• 그림목차 = ⅳ
• 표목차 = ⅷ
• 1장. 서론 = 1
• 2장. RF 때려내기 총과 in-situ 소형 진공조의 제작 = 7
• 2.1. 서론 = 7
• 2.2. 때려내기 파라미터 = 9
• 2.2.1. 때려내기 가스 = 10
• 2.2.2. 때려내기 전력 = 11
• 2.2.3. 차폐접지(ground shields) = 12
• 2.2.4. 표적냉각 = 13
• 2.2.5. 때려내기에서 맺음변수의 조절 = 13
• 2.2.6. 표적 파먹임(target erosion)과 박막의 두께분포 = 14
• 2.3. 때려내기 총의 설계 및 제작 = 16
• 2.3.1. 기존 2인치 때려내기 총에서의 공통적인 문제점들 = 16
• 2.3.2. 2인치 원형 고주파 때려내기 총의 제작 = 17
• 2.4. 제작된 때려내기 총의 성능평가 및 논의 = 19
• 2.5. In-situ 진공조의 설계 = 21
• 3장. 실험장치 및 방법 = 23
• 3.1. SnO₂박막의 성장장치 및 방법 = 23
• 3.2. In-situ와 ex-situ x-선 측정 = 25
• 3.2.1. X-선 실험방법 = 25
• 3.2.2. In-situ 실험 = 29
• 3.2.3. Ex-situ 실험 = 30
• 3.3. Atomic Force Microscopy(AFM) = 30
• 4장. SnO₂/Al₂O₃계의 구조 분석 = 32
• 4.1. 서론 = 32
• 4.2. X-선 산란을 이용한 구조분석 = 33
• 4.3. Grain 성장 dynamics = 43
• 5장. 작은 각 X-선 REFLECTIVITY = 55
• 5.1. Reflectivity 데이터 = 56
• 5.2. 박막의 두께와 correlated height fluctuation의 Fourier 변환을 이용한 빠른 계산 = 63
• 5.2.1. Layer stack의 결정 = 63
• 5.2.2. Height-height 상관함수의 결정 = 66
• 5.3. X-선 reflectivity에 관한 이론 = 71
• 5.3.1. 2층 박막의 Fresnel 반사 = 71
• 5.3.2. 거친 계면의 반사 = 73
• 6장. 성장 동력학 = 89
• 6.1. 동적 성장 이론 = 89
• 6.1.1. 서론 = 89
• 6.1.2. Self-similarity 와 self-affinity = 89
• 6.1.3. Self-affine 계면에 대한 성장지수들의 결정 = 95
• 6.1.4. Stochastic 성장 모델 = 96
• 6.1.5. 불연속(discrete) 성장 모델 = 100
• 6.2. Molecular beam epitaxy (MBE) 현상 = 104
• 6.2.1. 서론 = 104
• 6.2.2. MBE의 성장모델 = 108
• 6.2.3. 비국소적(nonlocal) 성장 모델 = 111
• 6.3. 실험결과로부터의 성장기구의 해석 = 114
• 6.3.1. 표면 형상으로부터의 성장 해석 = 114
• 6.3.2. Lateral correlation 함수 계산과 x-선 reflectivity = 124
• 7장. 결론 = 137
• 참고문헌 = 141
• ABSTRACT = 152