Title :
Deep UV sensors using surface acoustic wave oscillators fabricated on single crystalline AlN films grown on sapphire substrates
Author :
Laksana, Chipta P. ; Chen, Meei-Ru ; Kao, Hui-Ling ; Jeng, Erik S. ; Jian, Sheng-Rui
Author_Institution :
Dept. of Electron. Eng., Chung Yuan Christian Univ., Chungli, Taiwan
Abstract :
Epitaxial single crystal AlN thin films have been obtained on (001) sapphire substrates by helicon sputtering system at growth temperature of 450°C. Surface acoustic wave (SAW) filters were fabricated on AlN/sapphire. The center frequency is 354.2MHz, which corresponds to a phase velocity of 5667 m/s. The insertion loss and sidelobe rejection were about 24.9dB and 11.4dB, respectively. The value of TCF is measured to be -74.9 ppm/°C and -65.76 ppm/°C at 0.4 μm and 1 μm of film thickness, respectively. The temperature coefficient of frequency (TCF) of AlN/sapphire shows proportional to the film thickness. A frequency downshift about 43 KHz was observed when the UV source with the wavelength of around 200nm and 12 mW/cm2 of power density radiates the surface of SAW devices.
Keywords :
epitaxial growth; sapphire; sputtering; surface acoustic wave filters; surface acoustic wave oscillators; AlN; SAW filter; deep UV sensor; epitaxial single crystal AlN thin film; frequency 354.2 MHz; helicon sputtering system; insertion loss; phase velocity; sapphire substrate; sidelobe rejection; surface acoustic wave oscillator; temperature 450 C; temperature coefficient-of-frequency; Acoustic sensors; Acoustic waves; Crystallization; Filters; Frequency; Oscillators; Sputtering; Substrates; Surface acoustic waves; Temperature sensors; AlN; Helicon sputtering system; UV detector; surface acoustic wave (SAW) oscillators;
Conference_Titel :
Industrial Electronics and Applications (ICIEA), 2010 the 5th IEEE Conference on
Conference_Location :
Taichung
Print_ISBN :
978-1-4244-5045-9
Electronic_ISBN :
978-1-4244-5046-6
DOI :
10.1109/ICIEA.2010.5514720
