![]() ![]() ![]() Attal, “Design of a temperature stable surfaceĪcoustic wave device on silicon,”Electron Letters, vol. “Groupement de Recherche Coordonnees Microondes.” This work is supported by theĬentre National de la Recherche Scientifique under the The simulations show that SAW delay lines on GaAsĬan be temperature compensated with a layerof Si02 as in the Perhaps other materials achieve aīetter guiding of the SAW without additional perturbation of ![]() In addition the values of the t emperature coefficients of gold are The elastic constants of gold and GaAs are the same. ![]() The signs of the first-order temperature coefficient of SAW whereby the energy is concentrated mainly in the Si02 The TCD6 can be adjusted by varying the thickness of theĭepth distributionof the amplitudeof the mechanical displacement of the SAW. The thickness of gold required t o cancel the TCDo of the Variations of the different values of Si02 thickness. 2 shows up the effect of the gold-layer thickness on the 2 the temperature coefficients of the elastic constants of gold are given in [ 6 1.įig. The calculated variations of the TCDo in the structureĪu/Si02/GaAs are shown in Fig. This can be achievedīy loading the surface by a material slower than GaAs. Order for the Si02layer t o play its part, the wave energy must The part of the acoustic energy in the Si02 layeris not sufficient to balance the temperature effect of the substrate. Near thesurface as the Si02thickness increases. Thus, in the second case, the SAW is less confined Layer “stiffens” the GaAs substrate, that is, increases the SAW “loads” the silicon, that is, decreases the SAW velocity, whereas the Si02 The negative temperature coefficients of the GaAs substrate.Ĭomputer simulations show that Si02 layer 1 shows that the first-order TCDQ of the delay lineĬannot be cancelled, that is, the positive temperature coefficients of the elastic constants of the Si02 layer cannotbalance The temperature coefficients of theelastic constants of GaAs and Si02 areįig. 1, forĪ GaAs substrate 001-cut and 110propagation. No responsibility can be assumed by ThermoWorks for the accuracy or otherwise of the following figures.IEEE TRANSACTIONS ON SONICS AND ULTRASONICS, VOL. We would recommend, in the first instance, comparing measurements, found with an accurate surface probe or wire probe, and then the Infrared thermometer can be adjusted to match the correct emissivity and used for subsequent measurements. The accuracy of the following figures is almost impossible to guarantee as the emissivity of a surface will not only alter with regard to texture and colour but also with its actual temperature at the time of measurement. In the real world, there are no perfect "black bodies" and very few perfect infrared mirrors so most objects have an emissivity between 0 and 1. A material with an emissivity value of 0 would be considered a perfect thermal mirror.įor example, if an object had the potential to emit 100 units of energy but only emits 90 units in the real world, then that object would have an emissivity value of 0.90. A black body is a material that is a perfect emitter of heat energy and has an emissivity value of 1. It is defined as the fraction of energy being emitted relative to that emitted by a thermally black surface (a black body). Emissivity is a measure of the efficiency in which a surface emits thermal energy. ![]()
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