Growth of residual stress-free ZnO films on SiO2/Si substrate at room temperature for MEMS devices
TL;DR: In this paper, the residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 109 to 11.28 x 109 dyne/cm2 with compressive in nature.
Abstract: ZnO thick Stress relaxed films were deposited by reactive magnetron sputtering on 2”-wafer of SiO2/Si at room temperature. The residual stress of ZnO films was measured by measuring the curvature of wafer using laser scanning method and found in the range of 0.18 x 109 to 11.28 x 109 dyne/cm2 with compressive in nature. Sputter pressure changes the deposition rates, which strongly affects the residual stress and surface morphologies of ZnO films. The crystalline wurtzite structure of ZnO films were confirmed by X-ray diffraction and a shift in (0002) diffraction peak of ZnO towards lower 2θ angle was observed with increasing the compressive stress in the films. The band gap of ZnO films shows a red shift from ∼3.275 eV to ∼3.23 eV as compressive stress is increased, unlike the stress for III-nitride materials. A relationship between stress and band gap of ZnO was derived and proposed. The stress-free growth of piezoelectric films is very important for functional devices applications.
Citations
More filters
[...]
Northumbria University1, University of Electronic Science and Technology of China2, University of Bolton3, Griffith University4, University of Edinburgh5, University of Cambridge6, University of Manchester7, Technical University of Madrid8, Nanyang Technological University9, Tokyo Institute of Technology10
TL;DR: In this article, the authors acknowledge support from the Innovative electronic manufacturing research centre (IeMRC) through the EPSRC funded flagship project SMART MICROSYSTEMS.
Abstract: The authors acknowledge support from the Innovative electronic Manufacturing Research Centre (IeMRC) through the EPSRC funded flagship project SMART MICROSYSTEMS (FS/01/02/10), Knowledge Transfer Partnership No KTP010548, EPSRC project EP/L026899/1, EP/F063865/1; EP/F06294X/1, EP/P018998/1, the Royal Society-Research Grant (RG090609) and Newton Mobility Grant (IE161019) through Royal Society and NFSC, the Scottish Sensing Systems Centre (S3C), Royal Society of Edinburgh, Carnegie Trust Funding, Royal Academy of Engineering-Research Exchange with China and India, UK Fluidic Network and Special Interest Group-Acoustofluidics, the EPSRC Engineering Instrument Pool. We also acknowledge the National Natural Science Foundation of China (Nos. 61274037, 51302173), the Zhejiang Province Natural Science Fund (No. Z11101168), the Fundamental Research Funds for the Central Universities (No. 2014QNA5002), EP/D03826X/1, EP/ C536630/1, GR/T24524/01, GR/S30573/01, GR/R36718/01, GR/L82090/01, BBSRC/E11140. ZXT acknowledges the supports from the National Natural Science Foundation of China (61178018) and the NSAF Joint Foundation of China (U1630126 and U1230124) and Ph.D. Funding Support Program of Education Ministry of China (20110185110007) and the NSAF Joint Foundation of China (Grant No. U1330103) and the National Natural Science Foundation of China (No. 11304209). NTN acknowledges support from Australian Research Council project LP150100153. This work was partially supported by the European Commission through the 6th FP MOBILIS and 7th FP RaptaDiag project HEALTH-304814 and by the COST Action IC1208 and by the Ministerio de Economia y Competitividad del Gobierno de Espana through projects MAT2010-18933 and MAT2013-45957R.
281 citations
[...]
TL;DR: In this paper, structural, vibrational, photoluminescence and photo electron spectroscopic properties of rf magnetron sputtered ZnO films grown on unheated glass substrates are discussed.
Abstract: Structural, vibrational, photoluminescence and photo electron spectroscopic properties of rf magnetron sputtered ZnO films grown on unheated glass substrates are discussed. Variations in the c-axis orientation, average crystallite size, residual stress, and presence of disoriented grains, with varying oxygen content (40%–100%) during film growth are found to correlate with variation in the E2(high) and A1(LO) modes of the Raman spectra. Room temperature photoluminescence (RTPL) spectra exhibit a characteristic splitting in the near-band-edge emission (NBE) with three emission peaks (around 355, 386 and 395 nm) under an excitation wavelength of 290 nm. The blue emission (443–455 nm) is significantly controlled by oxygen vacancies and seen in films grown under 80% oxygen content. Quenching of NBE emission, for films prepared under oxygen rich ambient, is caused by the increased non-radiative recombination centers owing to reduced size of ZnO nano-crystallites. The shifts in the optical band gap of films grown under different oxygen content supplement the observed changes in the nano-crystallite size and luminescence properties. X-ray photoelectron spectroscopy confirms the fractional changes in the oxygen vacancy content in films deposited under different oxygen content in the sputtering gas.
60 citations
[...]
TL;DR: The study revealed that the excited electrons found pathway through PVA to ground state which was slower than the pure ZnO nanoparticles.
Abstract: ZnO:PVA nanocomposite films were prepared and their fluorescence and time resolved photoluminescence properties were discussed. X-ray diffraction and infrared spectroscopy results confirmed the ZnO:PVA interaction. Optical absorption spectra showed two bands at 280 and 367nm which were ascribed to PVA and excitonic absorption band, respectively. Fluorescence spectra showed that the blue emission of ZnO was enhanced about tenfold through chemical interface electron transfer. The electron transfer from ZnO to PVA and its decay dynamics were experimentally analyzed through time resolved fluorescence measurements. The study revealed that the excited electrons found pathway through PVA to ground state which was slower than the pure ZnO nanoparticles.
45 citations
[...]
TL;DR: In this article, an inverted hybrid perovskite solar cell using Al doped Zinc Oxide (AZO) transparent metal oxide as substrate and anode electrode was presented.
Abstract: In this study, we present an inverted hybrid perovskite solar cell using Al doped Zinc Oxide (AZO) transparent metal oxide as substrate and anode electrode. Obtained results revealed that the AZO substrates prepared by RF magnetron sputtering with the optimal growth parameters have electrical and optical properties similar to properties of commercial Indium Tin Oxide (ITO), resistivity around 0.5 mΩcm and transparency around 85%. Hybrid perovskite thin films were coated onto the PEDOT:PSS/AZO and PEDOT:PSS/ITO substrates. The morphological, structural and optical properties of the perovskite films were comparatively studied by SEM, XRD, and UV-visible spectroscopy. Besides, inverted planar perovskite solar cells were fabricated on AZO and on ITO substrates by single solution coating. The champion cell exhibited short-circuit current of 22.26 mA/cm2, an open-circuit voltage of 0.87 V, and a fill factor of 0.51, led to a power conversion efficiency (PCE) 9.88% which is obtained by cell based on AZO substrate. The PCE value is comparable to efficiency of cell based on ITO,12.82%.
26 citations
[...]
01 Nov 2019-Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms
TL;DR: In this paper, the impact of ion species and high energy photons irradiation on structured ZnO nanowires (ZnO-NWs) and at different ion energies (keV to MeV), ion fluences, and substrate temperatures are discussed.
Abstract: It is a misunderstanding that higher energy ion irradiation on nanomaterials has only detrimental effects on their properties. Recent research reveals that higher energy irradiation on nanostructure materials is favorable with advantageous effects. Light, medium, heavy ions, and high energy photons serve as a veritable tool to synthesized nanowires for these effects. In this article, experimental research on the impact of ion species and high energy photons irradiation on structured ZnO nanowires (ZnO-NWs) and at different ion energies (keV to MeV), ion fluences, and substrate temperatures are discussed. The study has revealed that ZnO-NWs structures were damaged at high irradiation fluence under room temperature. Moreover, the porous structures of ZnO-NWs are created by light ions irradiation at a higher temperature. It is noteworthy that the effect of these irradiation beams induced-cutting of ZnO-NWs and fabrication of nano-holes in ZnO-NWs valuable for nano-devices in space technology under harsh environment.
23 citations
References
More filters
[...]
TL;DR: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature.
Abstract: The semiconductor ZnO has gained substantial interest in the research community in part because of its large exciton binding energy (60meV) which could lead to lasing action based on exciton recombination even above room temperature. Even though research focusing on ZnO goes back many decades, the renewed interest is fueled by availability of high-quality substrates and reports of p-type conduction and ferromagnetic behavior when doped with transitions metals, both of which remain controversial. It is this renewed interest in ZnO which forms the basis of this review. As mentioned already, ZnO is not new to the semiconductor field, with studies of its lattice parameter dating back to 1935 by Bunn [Proc. Phys. Soc. London 47, 836 (1935)], studies of its vibrational properties with Raman scattering in 1966 by Damen et al. [Phys. Rev. 142, 570 (1966)], detailed optical studies in 1954 by Mollwo [Z. Angew. Phys. 6, 257 (1954)], and its growth by chemical-vapor transport in 1970 by Galli and Coker [Appl. Phys. ...
10,260 citations
[...]
TL;DR: This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.
Abstract: We have converted nanoscale mechanical energy into electrical energy by means of piezoelectric zinc oxide nanowire (NW) arrays. The aligned NWs are deflected with a conductive atomic force microscope tip in contact mode. The coupling of piezoelectric and semiconducting properties in zinc oxide creates a strain field and charge separation across the NW as a result of its bending. The rectifying characteristic of the Schottky barrier formed between the metal tip and the NW leads to electrical current generation. The efficiency of the NW-based piezoelectric power generator is estimated to be 17 to 30%. This approach has the potential of converting mechanical, vibrational, and/or hydraulic energy into electricity for powering nanodevices.
6,692 citations
[...]
TL;DR: It is well known that metallic films deposited electrolytically are in many cases liable to peel off if deposited to any considerable thickness as discussed by the authors, especially if it does not adhere very tightly to the body on which it is deposited.
Abstract: It is well known that metallic films deposited electrolytically are in many cases liable to peel off if deposited to any considerable thickness. This is the case with nickel which, when deposited over a certain thickness, will curl up into beautiful close rolls, especially if it does not adhere very tightly to the body on which it is deposited. For example, if a piece of glass is silvered by any of the usual silvering solutions, and then nickel is deposited on the silver, it is found that the nickel and silver peel off the glass in close tight rolls almost at once. In ‘Practical Electro-Chemistry,' by Bertram Blount, reference is made on pp. 114 and 272 to the tendency of nickel to peel off, and it is stated that it “will peel—spontaneously and without assignable cause” (p. 272), but that a thick coating can be obtained by keeping the solution at between 50° and 90°C. The late Earl of Rosse tried, about 1865, to make flat mirrors by coating glass with silver chemically, and then electroplating with copper; but he found that, owing to the “contraction” of the copper film, it became detached from the glass. I have had the' same experience in protecting silver 61ms in searchlight reflectors by a film of electro-deposited copper, it being found that if the film of copper is more than 0.01 mm. thick peeling is apt to take place.
4,253 citations
[...]
TL;DR: The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated in this article, where the optical dispersion data have been fitted to (1) a single oscillator model and (2) the Pikhtin-Yas'kov model.
Abstract: The influence of postdeposition annealing on the structural and optical properties of rf sputtered insulating zinc oxide films has been investigated. The as‐grown films deposited on quartz substrates were highly c‐axis oriented and in a state of stress. These films become almost stress free after a postdeposition annealing treatment at 673 K for 1 h in air. Above 673 K, a process of coalescence was observed which causes major grain growth resulting in microcrack formation and surface roughness. The refractive index shows a strong frequency dispersion below the interband absorption edge. The optical dispersion data have been fitted to (1) a single oscillator model and (2) the Pikhtin–Yas’kov model. The origin of optical dispersion at different annealing temperatures has been discussed in the light of these models. A packing density of more than 99% is estimated in the film annealed at 673 K, indicating that these films are almost void free.
559 citations
[...]
TL;DR: In this article, the effect of substrate-induced strain in polycrystalline ZnO thin films on different substrate, e.g., GaN epilayer, sapphire (0001), quartz glass, Si(111)∕SiO2, and glass deposited by sol-gel process, has been investigated by x-ray diffraction, scanning electron microscope, electrical resistivity, and photoluminescence measurements.
Abstract: The effect of substrate-induced strain in polycrystalline ZnO thin films on different substrate, e.g., GaN epilayer, sapphire (0001), quartz glass, Si(111)∕SiO2, and glass deposited by sol-gel process, has been investigated by x-ray diffraction, scanning electron microscope, electrical resistivity, and photoluminescence measurements. A strong dependence of orientation, crystallite size, and electrical resistivity upon the substrate-induced strain along the c axis has been found. The results of structural and morphological studies indicate that relatively larger tensile strain exists in ZnO deposited on sapphire and glass, while a smaller compressive strain appears in film deposited on GaN and the strain is relaxed in larger crystallite size. The electrical resistivity of the films increases exponentially with increasing strain. The excitonic peak positions are found to shift slightly towards lower energy side with increasing strain. The analysis shows that GaN being a closely lattice-matched substrate produces ZnO films of better crystallinity with a lower resistivity.
437 citations