| Autor: |
Okamoto, Norihiko L., Kusakari, Misato, Tanaka, Katsushi, Inui, Haruyuki, Yamaguchi, Masaharu, Otani, Shigeki |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 1/1/2003, Vol. 93 Issue 1, p88, 6p, 3 Charts, 5 Graphs |
| Abstrakt: |
Coefficients of thermal expansion (CTE) and elastic constants of single crystals of ZrB[sub 2] have been determined in the temperature ranges from room temperature to 1073 K and from room temperature to 1373 K, respectively. The elastic constants of ZrB[sub 2] are best characterized by the large value of the Young modulus (as high as 500 GPa) and the small values of the Poisson ratio (0.13-0.15), indicating the high stiffness and hardness and the brittleness, respectively. The values of CTE along the a- and c-axis directions are 6.66 × 10[sup -6] and 6.93 × 10[sup -6] K[sup -1], respectively, when averaged over the temperature range from room temperature to 1073 K. The CTE value along the a-axis direction of ZrB[sub 2] is only moderately larger than the corresponding value for GaN. This together with the small lattice mismatch along the a-axis direction between ZrB[sub 2] and GaN in the heteroepitaxial orientation relationship of (0001)[sub GaN]//(0001)[sub ZrB[sub 2]] and 〈11&2macr;0〉[sub GaN] //〈11&2macr;0〉[sub ZrB[sub 2]] indicate that only a small compressive stress develops in the GaN thin-film crystal grown on the (0001) surface of the ZrB[sub 2] substrate. The stresses developed in the GaN thin-film crystal are evaluated with the values of CTE and elastic constants of ZrB[sub 2] determined in the present study. The evaluation verifies the suitability of ZrB[sub 2] as a substrate for heteroepitaxial growth of GaN. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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