The defected acoustic band gap materials are promising a new generation of sensing technology based on layered cavities. We introduced a novel 1D defected phononic crystal (1D-DPC) as a high-sensitive gas sensor based on the Fano resonance transmitted window. Our designed (Lead–Epoxy) 1D-DPC multilayer has filled with a defect layer with different gases at different temperatures. In this study, Fano resonance—based acoustic band gap engineering has used to detect several gases such as O2, CO2, NH3, and CH4. For the first time, Fano resonance peaks appeared in the proposed gas sensor structures which attributed to high sensitivity, Q-factor, and figure-of-merit values for all gases. Also, the relation between the Fano resonance frequency and acoustic properties of gases at different temperatures has been studied in detail. The effect of the damping rate on the sensitivity of the gas sensor shows a linear behavior for CO2, O2, and NH3. Further, we introduced the effect of temperature on the damping rate of the incident waves inside the 1D-DPC gas sensor. The highest sensitivity and figure of merit were obtained for O2 of 292 MHz/(kg/m3) and 647 m3/Kg, respectively. While the highest figure-of-merit value of 60 °C−1 at 30 °C was attributed to O2. The transfer matrix method is used for calculating the transmission coefficient of the incident acoustic wave. We believe that the proposed sensor can be experimentally implemented.
The influence of the tilted electric field on the stability of the excited states of neutral donor impurity (D0) in a cylindrical quantum wire (CQW) is investigated. We consider the finite parabolic confinement potential in the CQW. The energies and wave functions for the on- and off-center D0 states are calculated using the variational principle within the single-band effective mass approximation. Moreover, the dependence of Stark shift ΔE in the ground and excited state energies of D0 on the tilted electric field are obtained. The tilted electric field strength is found to have a certain angle
at which the states of D0 turn from bound to unbound. For the off-center donor impurity in the intermediate region of the angle, the binding energy of D0 descends rapidly in both the strong and weak confinement regions, and it increases again in the limit of the total lateral electric field. Moreover, our results show a reordering of the on- and off-center D0 energy states when moving from the strong confinement region towards the weak confinement region. The ground state of the off-center D0 loses its stability, faster in the tilted electric field than both the normal and the total lateral electric fields. The Stark shift in D0 shows a blue shift, and in some states of D0, it increases quadratically with the enhancement in the tilted electric field.
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