Semiconductor light emitting element

• US 7,781,791 B2
• Filed: 02/22/2007
• Issued: 08/24/2010
• Est. Priority Date: 02/28/2006
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Okazaki, Tadahiro, Nakahara, Ken, Sakai, Mitsuhiko
• Primary Examiner(s): Tran; Tan N
• Application Number:
  US12/224,524
• Publication Number:
  US 20090026468A1
• Time in Patent Office: 1,279 Days
• Field of Search: 257/95, 257/98, 257/79, 257/E33.001
• US Class Current: 257/98
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

In a semiconductor light emitting element, a p-type layer (220), an active layer (230) and an n-type layer (240) are laminated on a substrate in this order. The n-type layer (240) is formed with a rectangular n-side electrode (241) whose width in one direction is equal to that of the n-type layer (240). The thickness t of the n-type layer (240) satisfies Formula 1 below. The semiconductor light emitting element includes a side surface (270) extending in the lamination direction and formed with a plurality of projections (271). Supposing that the wavelength of the light from the active-layer (230) is λ and the index of refraction of the n-type layer (240) or the p-type layer (220) is n, the average W_A of widths at bottoms of the projections is set to satisfy W_A≧λ/n.

$\begin{array}{cc}t\ge \frac{\rho J_{0}e}{4{\mathrm{\gamma \kappa }}_{B}T}·W\left(L-W\right)& \mathrm{Formula}1\end{array}$

• • where
  • L is width of the n-type layer in a direction different from the one direction,
  • T is absolute temperature,
  • W is width of the n-side electrode in a direction different from the one direction,
  • J₀ is current density at the contact portion between the n-side electrode and the n-type layer,
  • e is elementary charge,
  • γ is diode ideality factor,
  • κ_B is Boltzmann constant,
  • ρ is specific resistance of the n-type semiconductor layer.

Claims

1. A semiconductor light emitting element comprising:

a substrate; and

an n-type semiconductor layer, an active layer and a p-type semiconductor layer which are laminated on the substrate;

wherein the semiconductor light emitting element includes a side surface extending in a lamination direction and constituted by the substrate, the n-type semiconductor layer, the active layer and the p-type semiconductor layer, the side surface being formed with a plurality of projections except for the active layer, the plurality of projections being provided on the substrate, the n-type semiconductor layer and the p-type semiconductor layer,

wherein, when a wavelength of light emitted from the active layer is expressed by λ and

index of refraction of either one of the n-type semiconductor layer and the p-type semiconductor layer is expressed by n, average W_A of widths at bottoms of the projections satisfies;

W_A≧

λ

/n.

2. The semiconductor light emitting element according to claim 1, wherein at least one of the n-type semiconductor layer and the p-type semiconductor layer is made of GaN.

3. The semiconductor light emitting element according to claim 1, wherein the projections extend in the lamination direction and are triangular or semicircular in cross section.

4. The semiconductor light emitting element according to claim 1,

wherein each of the plurality of projections includes a surface inclined with respect to the lamination direction.

5. The semiconductor light emitting element according to claim 4, wherein each of the plurality of projections is cone-shaped.

6. The semiconductor light emitting element according to claim 4, wherein the substrate includes a prismatic portion and a tapered portion.