Design d'une lige à retard à onde acoustique de surface SAW destinée aux applications capteurs

Abstract

This work is based on the study and design of a SAW delay line based on IDT/Al1- xCrxN/Si hetero-structure to possibly achieve a temperature sensor that can be integrated into radio frequency (RF) circuits. In First, we used the functional density theory (DFT) implemented in two different codes: CASTEP and VASP in order to study the effect of the doping of AlN by Cr on the piezo-mechanical and acoustics properties of Al1-xCrxN thin films constituting the basis of the SAW delay line. We have found that doping considerably increases the piezoelectric modulus (d33). We optimized the parameters of the SAW IDT/Al1-xCrxN/Si delay lines (delay line length, number of fingers, etc.) and then designed this delay line using the Layout Editor software. The COM approach model combined with the P matrix was used to calculate the COM (Coupling of Modes) parameters of the SAW IDT/Al1-xCrxN/Si delay lines. Analysis of the performance of these delay lines by plotting the frequency response and the calculation of insertion loss revealed that the delay line SAW IDT/Al0.75Cr0.25N/Si is the most appropriate to design the temperature sensor.