In this study, the structural and nanomechanical properties of Cu₂O thin films are investigated by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy (SEM) and nanoindentation techniques. The Cu₂O thin films are deposited on the glass substrates with the various growth temperatures of 150, 250 and 350 °C by using radio frequency magnetron sputtering. The XRD results show that Cu₂O thin films are predominant (111)-oriented, indicating a well ordered microstructure. In addition, the hardness and Young’s modulus of Cu₂O thin films are measured by using a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. Results indicated that the hardness and Young’s modulus of Cu₂O thin films decreased as the growth temperature increased from 150 to 350 °C. Furthermore, the relationship between the hardness and films grain size appears to closely follow the Hall-Petch equation.

Berkovich nanoindentation-induced mechanical deformation mechanisms of AlN thin films have been investigated by using atomic force microscopy (AFM) and cross-sectional transmission electron microscopy (XTEM) techniques. AlN thin films are deposited on the metal-organic chemical-vapor deposition (MOCVD) derived Si-doped (2 × 1017 cm−3) GaN template by using the helicon sputtering system. The XTEM samples were prepared by means of focused ion beam (FIB) milling to accurately position the cross-section of the nanoindented area. The hardness and Young’s modulus of AlN thin films were measured by a Berkovich nanoindenter operated with the continuous contact stiffness measurements (CSM) option. The obtained values of the hardness and Young’s modulus are 22 and 332 GPa, respectively. The XTEM images taken in the vicinity regions just underneath the indenter tip revealed that the multiple “pop-ins” observed in the load–displacement curve during loading are due primarily to the activities of dislocation nucleation and propagation. The absence of discontinuities in the unloading segments of load–displacement curve suggests that no pressure-induced phase transition was involved. Results obtained in this study may also have technological implications for estimating possible mechanical damages induced by the fabrication processes of making the AlN-based devices.

Fluorine-doped tin oxide (FTO) thin films were deposited on glass substrates using ultrasonic spray pyrolysis (USP) at a fixed substrate temperature of 400 °C and various Fluorine/Tin (F/Sn) atomic ratios of 0, 0.1, 0.5, and 1.0. Effects of F/Sn atomic ratios on structural-morphological, compositional, electrical, optical, and nanomechanical properties of the FTO thin films were systematically studied. The FTO films exhibited a tetragonal structure with preferred orientations of (110), (200), and (211), and polycrystalline morphology with spear-like or coconut shell-like particles on the surfaces. The presence of F-doping was confirmed by XPS results with clear F1s peaks, and F-concentration was determined to be 0.7% for F/Sn = 0.1 and 5.1% for F/Sn = 0.5. Moreover, the resistivity of FTO films reduced remarkably from 4.1 mΩcm at F/Sn = 0 to 0.7 mΩcm at F/Sn = 1, primarily due to the corresponding increase of carrier concentration from 2 × 10²⁰ cm⁻³ to 1.2 × 10²¹ cm⁻³. The average optical transmittance of the films prepared at F/Sn of 0–0.5 was over 90%, and it decreased to 84.4% for the film prepared at F/Sn = 1. The hardness (H) and Young’s modulus (E) of the FTO films increased when the F/Sn ratios increased from 0 to 0.5, reaching maximum values of H = 12.3 ± 0.4 GPa, E = 131.7 ± 8.0 GPa at F/Sn = 0.5. Meanwhile, the H and E reduced considerably when the F/Sn ratio further increased to 1.0, following the inverse Hall-Petch effect approximately, suggesting that the grain boundary effect played a primary role in manipulating the nanomechanical properties of the FTO films. Furthermore, favorable mechanical properties with large H/E_f and $H^3/E_f^2$ ratios were found for the FTO film prepared at F/Sn = 0.5, which possessed high crystallinity, large grain size, and compact morphology.

Details of Berkovich nanoindentation-induced mechanical deformation mechanisms of single-crystal Si(100) and the metal-organic chemical-vapor deposition (MOCVD) derived GaN thin films have been systematic investigated by means of micro-Raman spectroscopy and cross-sectional transmission electron microscopy (XTEM) techniques. The XTEM samples were prepared by using focused ion beam (FIB) milling to accurately position the cross-section of the nanoindented area. The behaviors of the discontinuities displayed in the loading and unloading segments of the load-displacement curves of Si and GaN thin films performed with a Berkovich diamond indenter tip were explained by the observed microstructure features obtained from XTEM analyses. According to the observations of micro-Raman and XTEM, the nanoindentation-induced mechanical deformation is due primarily to the generation and propagation of dislocations gliding along the pyramidal and basal planes specific to the hexagonal structure of GaN thin films rather than by indentation-induced phase transformations displayed in Si.

This study reports the surface roughness and nanomechanical characteristics of ZnO thin films deposited on the various substrates, obtained by means of atomic force microscopy (AFM), nanoindentation and nanoscratch techniques. ZnO thin films are deposited on (a- and c-axis) sapphires and (0001) 6H-SiC substrates by using the pulsed-laser depositions (PLD) system. Continuous stiffness measurements (CSM) technique is used in the nanoindentation tests to determine the hardness and Young’s modulus of ZnO thin films. The importance of the ratio (H/E _film) of elastic to plastic deformation during nanoindentation of ZnO thin films on their behaviors in contact-induced damage during fabrication of ZnO-based devices is considered. In addition, the friction coefficient of ZnO thin films is also presented here.