Growth of high-quality one-inch free-standing heteroepitaxial (001) diamond on (11 2 ¯ 0) sapphire substrate

Abstract

One-inch free-standing (001) diamond layers on a (11 2 ¯0) (a-plane) sapphire substrate with an Ir buffer layer (Kenzan Diamond®) were grown. The full-width at half maximum values of (004) and (311) X-ray rocking curves were 113.4 and 234.0 arc sec, respectively. The dislocation density of the substrates was 1.4 × 107 cm-2, determined by plan-view transmission electron microscopy observation. These values are much lower than the reported values among heteroepitaxial diamonds. Furthermore, X-ray pole figure measurements showed four symmetry of the crystal, showing single crystallinity without any twinning. The curvature radius of diamond was measured to be 90.6 cm, which is much larger than previous values, ca. 20 cm. Surprisingly, a cubic-lattice (001) diamond crystal was epitaxially grown on a trigonal-lattice (11 2 ¯0) sapphire substrate. However, we found that the epitaxial relation is diamond (001) [110]//Ir (001) [110]//sapphire (11 2 ¯0) [0001]. Now, high-quality one-inch diamond wafers will be available as a substrate used for diamond electronic devices.