Browsing by Author "Lai, Y. -S."

Now showing 1 - 3 of 3

Cross-sectional transmission electron microscopy studies for deformation behaviors of AlN thin films under Berkovich nanoindentation
(2010-08-01)
Jian, Sheng-Rui
;
Chen, G. -J.
;
Chen, H. -G.
;
Jang, Jason S. -C.
;
Liao, Y. -Y.
This article reports a nanomechanical response study of the contact-induced deformation behavior in AlN thin film by using a combination of nanoindentation and the cross-sectional transmission electron microscopy (XTEM) techniques. AlN thin films are deposited on Si(1 1 1) substrates by using the helicon sputtering system. The hardness and Young's modulus of the AlN thin film are measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) mode. The obtained values of hardness and Young's modulus are 24.79 +/- 0.33 GPa and 223.92 +/- 5.34 GPa, respectively. XTEM samples are prepared by using focused ion beam (FIB) milling to accurately position the cross-section of the indented area. Although the film's surface was free from fracture, AlN thin film showed evidence of radial crack along the columnar grain boundary underneath the center of Berkovich indentation for an applied load of 100 mN. XTEM results also indicated that the slip bands on {1 1 1} planes and an indentation-induced phase transformation zone of silicon substrate, containing the metastable phases of Si-III and Si-XII, and, the amorphous phases are observed. (C) 2010 Elsevier B.V. All rights reserved.
Influence of annealing temperature on the structural, optical and mechanical properties of ALD-derived ZnO thin films
(2011-06-15)
Yen, C. -Y.
;
Jian, S. -R.
;
Chen, G. -J.
;
Lin, C. -M.
;
Lee, H. -Y.
ZnO thin films grown on Si(1 1 1) substrates by using atomic layer deposition (ALD) were annealed at the temperatures ranging from 300 to 500 degrees C. The X-ray diffraction (XRD) results show that the annealed ZnO thin films are highly (0 0 2)-oriented, indicating a well ordered microstructure. The film surface examined by the atomic force microscopy (AFM), however, indicated that the roughness increases with increasing annealing temperature. The photoluminescence (PL) spectrum showed that the intensity of UV emission was strongest for films annealed at 500 degrees C. The mechanical properties of the resultant ZnO thin films investigated by nanoindentation reveal that the hardness decreases from 9.2 GPa to 7.2 GPa for films annealed at 300 degrees C and 500 degrees C, respectively. On the other hand, the Young's modulus for the former is 168.6 GPa as compared to a value of 139.5 GPa for the latter. Moreover, the relationship between the hardness and film grain size appear to follow closely with the Hall-Petch equation. (C) 2011 Elsevier B. V. All rights reserved.
Rapid thermal annealing effects on the structural and nanomechanical properties of Ga-doped ZnO thin films
(2013-09-01)
Jian, S. -R.
;
Chen, G. -J.
;
Wang, S. -K.
;
Lin, T. -C.
;
Jang, J. S. -C.
In this study, the structural and nanomechanical properties of Ga-doped ZnO (GZO) thin films on glass substrates followed by rapid thermal annealing (RTA) process were investigated by X-ray diffraction (XRD), atomic force microscopy (AFM) and nanoindentation techniques. The XRD results indicated that the annealed GZO thin films are textured, having a preferential crystallographic orientation along the hexagonal wurtzite (002) axis. Both the grain size and surface roughness of the annealed GZO thin films exhibit an increasing trend after RTA treatment. The hardness and Young's modulus of the annealed GZO thin films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. Furthermore, the hardness and Young's modulus were found to increase with increasing grain size when the RTA time was prolonged from 0.5 to 3 min. The deformation behavior is referred to the inverse Hall-Petch effect commonly observed in systems deformed primarily via grain boundary sliding. The suppression of dislocation movement-associated deformation mechanism might be arisen from strong pinning effects introduced by Ga-doping. (C) 2012 Elsevier B.V. All rights reserved.