Browsing by Author "Dai, Ching-Liang"

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Effect of annealing temperature for Si0.8Ge0.2 epitaxial thin films
(2008-03-15)
Chang, Yuan-Ming
;
Dai, Ching-Liang
;
Cheng, Tsung-Chieh
;
Hsu, Che-Wei
;
機械工程學系
This study investigates the effect of annealing temperature on the Si0.8Ge0.2 epitaxial layers. The Si0.8Ge0.2 epitaxial layers were deposited by using ultrahigh vacuum chemical vapor deposition (UHVCVD) with different annealing temperatures ((400-1000 degrees C). Various measurement technologies, including high-resolution X-ray diffraction ((HRXRD), atomic force microscopy ((AFM) and interfacial adhesion tester, were used to characterize the materials properties of the SiGe epilayers. The experimental results showed that the SiGe epilayers gradually reduced lattice-mismatch to the underlying substrate as annealing temperature increased (from 400 to 800 degrees C), which resulted from a high temperature enhancing interdiffusion between the epilayers and the underlying substrate. In addition, the average grain size of the SiGe films increased from 53.3 to 58 nm with increasing annealing temperature. The surface roughness in thin film annealed at 800 degrees C was 0.46 nm. Moreover, the interfacial adhesion strength increased from 476 +/- 9 to 578 +/- 12 kg/cm(2) with increasing the annealing temperature. (c) 2007 Elsevier B.V. All rights reserved.
Nanocone SiGe antireflective thin films fabricated by ultrahigh-vacuum chemical vapor deposition with in situ annealing
(2010-05-03)
Chang, Yuan-Ming
;
Dai, Ching-Liang
;
Cheng, Tsung-Chieh
;
Hsu, Che-Wei
;
機械工程學系
In this study, we fabricated nanocone-presenting SiGe antireflection layers using only ultrahigh-vacuum chemical vapor deposition. In situ thermal annealing was adopted to cause SiGe clustering, yielding a characteristic nanocone array on the SiGe surface. Atomic force microscopy indicated that the SiGe nanocones had uniform height and distribution. Spectrophotometric measurements revealed that annealing at 900 degrees C yielded SiGe thin films possessing superior antireflective properties relative to those of the as-grown SiGe sample. We attribute this decrease in reflectance to the presence of the nanostructured cones. Prior to heat treatment, the mean reflectance of ultraviolet rays (wavelength <400 nm) of the SiGe thin film was ca. 61.7%; it reduced significantly to less than 28.5% when the SiGe thin film was annealed at 900 degrees C. Thus, the drop in reflectance of the SiGe thin film after thermal treatment exceeded 33%. (C) 2010 Elsevier B.V. All rights reserved.