Jpn. J. Appl. Phys. 44 (2005) pp. L564-L565 |Previous Article| |Next Article| |Table of Contents|
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Letter
Temperature Dependence of Surface Acoustic Wave Characteristics of GaN Layers on Sapphire Substrates
Kazumi Nishimura,
Naoteru Shigekawa,
Haruki Yokoyama and
Kohji Hohkawa1
NTT Photonics Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi-shi, Kanagawa 243-0198, Japan
1Kanagawa Institute of Technology, 1030 Shimo-Ogino, Atsugi-shi, Kanagawa 243-0292, Japan
(Received January 31, 2005; accepted March 7, 2005; published April 15, 2005)
We measured surface acoustic wave (SAW) characteristics along the [01-10] and [2-1-10] directions of 1.5- and 2-µm-thick GaN layers on (0001) sapphire substrates at ambient temperatures between -50 and 200°C. The extracted thermal coefficient of delay (TCD) for the SAW propagating along the [01-10] direction, which is smaller than that for the SAW propagating along the [2-1-10] direction, decreases when GaN layer thickness, h, multiplied by SAW wave number, k, increases. The TCD for hk = 3.9, which might be close to that in bulk GaN, is as small as 28.3 ppm/deg. These results indicate that GaN is promising for SAW device operation over a wide range of ambient temperatures.
URL:
http://jjap.jsap.jp/link?JJAP/44/L564/
DOI: 10.1143/JJAP.44.L564
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