Pattern wafer for LEDs, epitaxial wafer for LEDs and method of manufacturing the epitaxial wafer for LEDs

Patent metadata

Field	Value
Publication number	US-9660141-B2
Application number	US-201414894480-A
Country	US
Kind code	B2
Filing date	May 28, 2014
Priority date	May 31, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A pattern wafer ( 10 ) for LEDs is provided with an uneven structure A ( 20 ) having an arrangement with n-fold symmetry substantially on at least a part of the main surface, where in at least a part of the uneven structure A ( 20 ), a rotation shift angle Θ meets 0°<Θ≦(180/n)° in which Θ is the rotation shift angle of an arrangement axis A of the uneven structure A ( 20 ) with respect to a crystal axis direction in the main surface, and a top of the convex-portion of the uneven structure A ( 20 ) is a corner portion with a radius of curvature exceeding “0”. A first semiconductor layer ( 30 ), light emitting semiconductor layer ( 40 ) and second semiconductor layer ( 50 ) are layered on the uneven structure A ( 20 ) to constitute an epitaxial wafer ( 100 ) for LEDs. It is possible to provide the pattern wafer for LEDs and epitaxial wafer for LEDs with cracks and internal quantum efficiency IQE improved.

First claim

The invention claimed is:

1. A pattern wafer for an LED, comprising:
an uneven structure A having an arrangement with n-fold rotational symmetry on at least a part of a main surface, wherein
in at least a part of the uneven structure A, a minimum rotational shift angle Θ satisfies 0°<Θ≦(180/n)°, wherein Θ is the minimum rotational shift angle of an arrangement axis A of the uneven structure A relative to a crystal axis direction of the pattern wafer for an LED in the main surface, and
each top of convex-portions of the uneven structure A is formed as a curved surface having a radius of curvature exceeding “0”.

2. The pattern wafer for an LED according to claim 1 , wherein the pattern wafer is further provided with an uneven structure L, different from the uneven structure A, having an arrangement with m-fold rotational symmetry, wherein m is a integer of 2 or more.

3. The pattern wafer for an LED according to claim 2 , wherein the uneven structure L is comprised of pluralities of convex portions and concave portions having a first average interval (PL), the uneven structure A is provided on surfaces of at least either the convex portions or the concave portions forming the uneven structure L, and is comprised of pluralities of convex portions and concave portions having a second average interval (PA), and a ratio (PL/PA) of the first average interval (PL) to the second average interval (PA) exceeds 1 and is 2000 or less.

4. The pattern wafer for an LED according to claim 3 , wherein a plurality of the convex portions forming the uneven structure L is mutually spaced, and a plurality of the convex portions or the concave portions forming the uneven structure A is provided at least in bottom portions of a plurality of the concave portions forming the uneven structure L.

5. The pattern wafer for an LED according to claim 3 , wherein a plurality of the concave portions forming the uneven structure L is mutually spaced, and a plurality of the convex portions or the concave portions forming the uneven structure A is provided at least on tops of a plurality of the convex portions forming the uneven structure L.

6. The pattern wafer for an LED according to claim 3 , wherein a coverage of the uneven structure A to the uneven structure L exceeds 0% and is less than 100%.

7. The pattern wafer for an LED according to claim 2 , wherein the uneven structure A is comprised of pluralities of convex portions and concave portions having a first average interval (PA), the uneven structure L is provided on a surface of the uneven structure A apart from each other so that a part of the uneven structure A is exposed, and is comprised of a plurality of convex portions having a second average interval (PL), and a ratio (PL/PA) between the first average interval (PA) and the second average interval (PL) exceeds 1 and is 2000 or less.

8. The pattern wafer for an LED according to claim 1 , wherein an average interval Pave of the uneven structure A meets 50 nm≦Pave≦1500 nm.

9. The pattern wafer for an LED according to claim 1 , wherein in using a Duty (ΦDave/Pave) that is a ratio of an average diameter (Φave) of a bottom of the convex-portion of the uneven structure A to an average interval Pave, the minimum rotational shift angle Θ meets a range of a tan(Duty/2)°≦Θ≦(180/n)°.

10. The pattern wafer for an LED according to claim 1 , wherein the pattern wafer for an LED is a sapphire wafer, a silicon wafer, a silicon carbide wafer or a gallium nitride-based wafer.

11. An epitaxial wafer for an LED, wherein at least a first semiconductor layer, a light emitting semiconductor layer and a second semiconductor layer are layered in this order on the main surface provided with the uneven structure A of the pattern wafer for an LED according to claim 1 .

12. The epitaxial wafer for an LED according to claim 11 , wherein a ratio (Hbun/Have) of a distance (Hbun) between a surface on the light emitting semiconductor layer side of the pattern wafer for an LED and a surface on the first semiconductor layer side of the light emitting semiconductor layer to an average height (Have) of the uneven structure A meets 2≦Hbun/Have≦300.

13. The epitaxial wafer for an LED according to claim 11 , wherein the first semiconductor layer contains an undoped first semiconductor layer and a doped first semiconductor layer sequentially layered from the pattern wafer for an LED side, and a ratio (Hbu/Have) of a distance (Hbu) between a surface on the light emitting semiconductor layer side of the pattern wafer for an LED and a surface on the doped first semiconductor layer side of the undoped first semiconductor layer to an average height (Have) of the uneven structure A meets 1.5≦Hbu/Have≦200.

Assignees

• Asahi Kasei E Materials Corp

Inventors

• Koike Jun

Classifications

• H10P74/203

  Structural properties, e.g. testing or measuring thicknesses, line widths, warpage, bond strengths or physical defects · CPC title

• H10P14/3416

  Nitrides · CPC title

• H10P14/3216

  Nitrides · CPC title

• H10P14/2925

  Surface structures · CPC title

• H10P14/2901

  Materials · CPC title