Fabrication of 5-GHz-band SAW filter with atomically-flat-surface aln on sapphire

Abstract

5-GHz-band surface acoustic wave (SAW) filters for mobile communication were fabricated on atomicallyflat-surface (0001)aluminum nitride/(0001)sapphire (AlN/Al2O3) combination. The SAW devices were fabricated using electron beam lithography and lift-off method. Atomically-flat-surface AlN films were used to reduce SAW propagation loss. Center frequency of the fabricated SAW filter was 5.18 GHz. SAW velocity was 5688 m/s at normalized thickness by wave number (kH) of 9.9. Effective coupling coefficient was 0.1 % and temperature-coefficient of delay was 9 ppm/ • C at kH of 5.9. SAW propagation loss was 0.0053 dB at 5.18 GHz. The atomically-flatsurface (0001)AlN/(0001)Al2O3 combination is promised to be used for 5-GHz-band SAW filter for the application to mobile communication.

Investigations of SAW delay lines on c-plane AlN/sapphire at elevated temperatures

“…Because of the high velocity of the SAW Rayleigh waves on AlN/sapphire substrates, high frequencies can be reached [2]. This helps to correct the frequency shifts caused by mass loading effects, without reaching limits of optical I-line lithography.…”

Epitaxial Growth of Sc0.09Al0.91N and Sc0.18Al0.82N Thin Films on Sapphire Substrates by Magnetron Sputtering for Surface Acoustic Waves Applications

“…In this context, sapphire substrates are highly compatible with AlN films as they show concurrently high temperature stability, high dielectric properties, comparable SAW velocities, and they enable the growth of highly textured AlN films [17]. Finally, the AlN/sapphire structure exhibits relatively low propagation losses at high frequencies [18]. One major result concerning the use of the AlN/sapphire bilayer structure for high-temperature SAW applications consisted of the measurement of a SAW signal on a wired delay line for 40 h at 1050 • C [19].…”

Fabrication of High Frequency Surface Acoustic Wave (SAW) Devices for Real Time Detection of Highly Toxic Chemical Vapors

“…SAW devices can be used to monitor/sense gases and organic solvents, if these are coated with a material which selectively adsorbs molecules from air (Wohltjen 1984 The use of diamond in the multilayered SAW structure has the following advantages: high frequencies up to 5 GHz, high coupling coefficients up to 1.2%, small temperature deviations, high power capability, and small device size without submicron lithography [6].…”