Phosphor thermography, relying on the temperature dependence of the decay time of photoluminescence from suitable phosphors, provides remote measurement of the temperature of components. Such a phosphor is yttrium oxide doped with europium (Y2O3:Eu). Associated with this phosphor is also a rise time. Demonstrated is that the rise time is also temperature dependent, as a result of known electronic transitions within the Eu ions. For the phosphor Y2O3:Eu (3.4 at.%), the rise time is an activated process in the temperature region between 25 and 850 °C. Faster than the decay time, the rise time offers the opportunity for measurement of higher velocity components.
Abstract:Tin doped indium oxide (ITO) has been directly deposited onto a variety of flexible materials by a reactive sputtering technique that utilises a remotely generated, high density plasma. This technique, known as high target utilisation sputtering (HiTUS), allows for the high rate deposition of good quality ITO films onto polymeric materials with no substrate heating or post deposition annealing. Coatings with a resistivity of 3.8 ×10−4 Ωcm and an average visible transmission of greater than 90% have been deposited onto PEN and PET substrate materials at a deposition rate of 70 nm/min. The electrical and optical properties are retained when the coatings are flexed through a 1.0 cm bend radius, making them of interest for flexible display applications.
Abstract. An investigation into the modification of low temperature deposited ZnO thin films by different annealing processes has been undertaken using laser, thermal and rapid thermal annealing of 60nm ZnO films deposited by Hi-Target-Utilization-Sputtering. Single pulse laser annealing using a KrF excimer laser ( A = 248nm) over a range of fluences up to 315 mJ/cm 2 demonstrates controlled indepth modification of internal film microstructure and luminescence properties without the film degradation produced by high temperature thermal and RTA processes. Photoluminescence properties show that the ratio of defect related deep level emission (DLE, 450nm -750nm, 2.76eV-1.65eV) to excitonic near band-edge emission (NBE at 381nm, 3.26eV) is directly correlated to processing parameters. Thermal and rapid thermal processing results in the evolution of a strong visible orange/red DLE photoluminescence (with peaks at 590nm, 2.10eV and 670nm, 1.85eV) dominated by defects related to excess oxygen. At higher temperatures, the appearance of a green/yellow emission (530nm, 2.34eV) indicates a transition of the dominant radiative transfer mechanism. In contrast, laser processing removes defect related DLE and produces films with intense NBE luminescence, correlated to the observed formation of large grains (25-40nm IntroductionThin films of ZnO are of interest across a range of optoelectronic and sensor device applications due to ZnO being a wide gap (>3 eV) n-type semiconductor with a high exciton binding energy [1] and a piezoelectric response [2]. Poly crystalline thin films of ZnO are deposited by a variety of physical and chemical vapour methods, with sputtering [1] being a preferred choice for low cost and scalability. However, to achieve the desired thin film properties, particularly for low temperature deposited films, it is critical to control grain microstructure, surface morphology, and internal defects [3]. Techniques that have been previously reported to improve these properties of ZnO thin films include post deposition thermal annealing [4,5], rapid thermal annealing [6,7], and laser annealing [8,9,10]. In this paper we present the results from a comparative study of the effect of all three of these annealing processes on the microstructure, crystallinity and associated intrinsic photoluminescence properties of low temperature sputter deposited ZnO thin films. The results demonstrate that pulsed laser annealing is a powerful tool for the controlled modification of low temperature deposited thin films. In particular, the work presented here explores the effect of a more comprehensive range of laser processing parameters on low temperature ZnO thin films than previously reported. The results
Phosphor thermography is a laser-induced fluorescence method utilized for the temperature sensing of rotating components within inhospitable environments. Results presented here show that thin film coatings for thermographic sensors have a much higher durability than conventional thick film coatings. Room-temperature measurements demonstrate that the intensity of the luminescent emission from thin films is equivalent to that from thick films. Lifetime measurements carried out at C show that thin films survived for up to ten hours, whereas thick film samples survived for less than one. More importantly, post-run measurements of thin films indicate little degradation in the intensity of the fluorescent signal. This illustrates the capability of thin film sensors for remote temperature sensing.
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