High-temperature 434 MHz surface acoustic wave devices based on GaPO/sub 4/

Abstract

Research into surface acoustic wave (SAW) devices began in the early 1970s and led to the development of high performance, small size, and high reproducibility devices. Much research has now been done on the application of such devices to consumer electronics, process monitoring, and communication systems. The use of novel materials, such as gallium phosphate (GaPO4), extends the operating temperature of the elements. SAW devices based on this material operating at 434 MHz and up 800 C, can be used for passive wireless sensor applications. Interdigital transducer (IDT) devices with platinum/zirconium metallization and 1.4 m finger-gap ratio of 1:1 have been fabricated using direct write e-beam lithography and a lift-off process. The performance and long-term stability of these devices has been studied, and the results are reported in this paper.

High-Temperature Piezoelectric Sensing

“…Hamidon et al have developed a high-temperature surface acoustic wave device using gallium orthophosphate (GaPO 4 ) with operating frequency of 434 MHz and temperatures up to 600 °C [65]. Interdigital transducers (IDTs) were fabricated using an e-beam lithography coupled with a lift-off technique on the GaPO 4 crystal plate.…”

“…The S 11 parameters measurement results as a function of frequency at 600 °C for 301 h [65] (copyright 2006 by the IEEE).…”

Wireless sensor applications in extreme aeronautical environments

“…Aluminum nitride is being investigated for high temperature (800°C) operation of temperature compensating sensors [9]. Gallium phosphate (GaPO) has been used as a substrate in the development of a temperature sensor [10]. The sensor is wireless, operates at 433 MHz, and withstands temperatures of 600°C for 192 hours.…”

Passive wireless SAW sensors for IVHM

“…Aluminum nitride is being investigated for high temperature (800°C) operation of temperature compensating sensors [23]. Gallium phosphate (GaPO) has been used as a substrate in the development of a temperature sensor [24]. The sensor is wireless, operates at 433 MHz, and withstands temperatures of 600°C for 192 hours.…”