Crystal substrate

Abstract

To provide a technique for further reducing a dislocation density in a crystal substrate composed of a group III nitride.SOLUTION: A crystal substrate is a substrate composed of a group III nitride single crystal, a low-index crystal plane most proximate to a principal surface of the substrate is a c-plane, a threading dislocation included in the single crystal and penetrating the c-plane extends in a thickness direction without bending in a direction orthogonal to the thickness direction of the substrate, and a ratio of edge dislocations in the threading dislocations is less than 60%.SELECTED DRAWING: Figure 12

Claims

1. A substrate made of a single crystal of a group III nitride, wherein the lowest index crystal plane closest to the main surface of the substrate is the c-plane. The through-dislocations that penetrate the c-plane contained in the single crystal extend in the thickness direction without bending in a direction perpendicular to the thickness direction of the substrate. The radius of curvature of the c-plane of the single crystal in the a-axis direction and the radius of curvature in the m-axis direction are both 20m or more. The average penetration dislocation density on the main surface of the single crystal is 3 × 10⁵ / cm² or less. A crystalline substrate in which the ratio of edge dislocations to the aforementioned through dislocations is less than 60%.

2. The oxygen concentration in the aforementioned single crystal is 1 × 10 １７ / cm ３ A crystal substrate according to claim 1, wherein the value is less than [value missing].

3. The crystalline substrate according to claim 1 or 2, wherein the threading dislocations contained in the single crystal do not include helical dislocations.

4. The maximum penetration dislocation density on the main surface of the single crystal is 5 × 10 ５ / cm ２ The crystal substrate according to any one of claims 1 to 3 below.

5. The crystal substrate according to any one of claims 1 to 4, wherein the ratio of the maximum dislocation density to the minimum threading dislocation density on the main surface of the single crystal is 100 times or less.

6. The hydrogen concentration in the aforementioned single crystal is 1 × 10⁻⁶ １７ / cm ３ A crystal substrate according to any one of claims 1 to 5, wherein the value is less than [value missing].

7. The crystal substrate according to any one of claims 1 to 6, wherein the main surface of the substrate does not have any dislocation concentration regions with a through-dislocation density of 1 × 10⁷ / cm² or more.

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