Temperature stability of ZnO thin film SAW device on fused quartz

Abstract

Surface acoustic wave (SAW) filters for lowfrequency (38-65 MHz) applications have been developed using a radio frequency (RF)-magnetron-sputtered ZnO film on fusedquartz substrates. SAW propagation characteristics such as electromechanical coupling coefficient (K 2 ), SAW phase velocity (v), insertion loss, and temperature coefficient of delay (TCD) have been measured. The intergidital transducer (IDT)/ZnO/fusedquartz device structure yields almost zero TCD (1 ppm · • C −1 ) with 0.316 λ thick ZnO layer (for the device operating at 60 MHz). Alternately, an overlayer of positive TCD material (ZnO itself) has also been deposited on the IDT/ZnO(< 0.316 λ)/fused-quartz device at a low substrate temperature to reduce the TCD. A modified layered structure consisting of ZnO/IDT/ZnO/fused quartz yields almost zero TCD (−3 ppm · • C −1 ) with a 5.3-µm-thick ZnO overlayer and a 8.1-µm-thick (0.183 λ) ZnO bottom layer. Experimentally obtained SAW propagation characteristics have been compared with the theoretical results. Index Terms-Deposition by sputtering (81.15.Cd), filters (84.30.Vn), surface acoustic waves (SAWs) in piezoelectrics (77.65.Dq), thermal stability (68.60.Dv).

Influence of stress on the structural and dielectric properties of rf magnetron sputtered zinc oxide thin film

“…8,9 In most of these studies, the presence of stress in the deposited ZnO films has been identified as a critical parameter and may affect the performance of the devices due to change in electrical and optical properties. [2][3][4][5][6][7][8][9] Various deposition techniques are being used to grow highly c-axis oriented zinc oxide thin films and each technique has its own advantages and disadvantages. 1 The rf magnetron sputtering is found to be the most suitable technique due to better control over stoichiometry and deposition of uniform film.…”

Temperature stability of ZnO-based Love wave biosensor with SiO2 buffer layer

“…The effect of temperature on SAW propagation characteristics is typically characterized in terms of temperature coefficient of delay (TCD) given by [6,7]:…”

“…Since a 2 for the materials used in the present layered configurations were not available in the literature, we restrict our calculations to use a 1 only. The material constants and temperature coefficients used in the calculations have been reported in [7] and summarized in Table 1.…”

“…The SAW propagation characteristics of the ZnO/Si layered structure are expected to be influenced by the change of ambient temperatures, since ZnO and Si materials have negative and positive temperature coefficients of delay (TCD), respectively [6][7][8].…”

ZnO Thin Films Synthesized by Sol-Gel Process for Photonic Applications

“…Unlike many of its competitors, ZnO is inexpensive, relatively abundant, chemically stable, easy to prepare, non toxic and most of the doping materials that are used with it are also readily available. It has been used in a variety of applications such as conductive films, solar cell windows, photoelectric cells, nonlinear optics, bulk and surface acoustic wave devices [1][2][3], and micro mechanic devices [4,5]. ZnO wide band gap opens the possibility of creating ultraviolet (UV) light emission diodes (LEDs) and white LEDs with superior color purity.…”