Surface acoustic wave device, electronic apparatus, and sensor apparatus

A surface acoustic wave device comprising:

• a quartz crystal substrate having Euler angles (−1.5°≦φ≦1.5°, 117°≦θ≦142°, |ψ|≠90°×n (where n=0, 1, 2, 3));
• and
• an IDT which has a plurality of electrode fingers on the principal surface of the quartz crystal substrate and excites a Rayleigh wave in a stopband upper end mode,
• wherein inter-electrode-finger grooves are recessed in the surface of the quartz crystal substrate between adjacent electrode fingers of the IDT,
• the wavelength λ of the Rayleigh wave and the depth G of the inter-electrode-finger grooves satisfy 0.01λ≦G≦0.07λ,
• an IDT line occupancy η and the depth G of the inter-electrode-finger grooves satisfy the following relationships:
• −2.0000×G/λ+0.7200≦η≦−2.5000×G/λ+0.7775 where 0.0100λ≦G≦0.0500λ;
• −3.5898×G/λ+0.7995≦η≦−2.5000×G/λ+0.7775 where 0.0500λ≦G≦0.0695λ;
• and
• a frequency-temperature characteristic is expressed by a curve having a maximum value, a minimum value, and an inflection point between the maximum value and the minimum value, and the temperature of the inflection point is adjustable depending on the IDT line occupancy so as to be within a range of ±30° C. from the center temperature Tc of a desired operation temperature range.