Semiconductor Light Emitting Element

US 20090026468A1
Filed: 02/22/2007
Published: 01/29/2009
Est. Priority Date: 02/28/2006
Status: Active Grant

First Claim

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1. A semiconductor light emitting element comprising:

a substrate;

a p-type semiconductor layer supported by the substrate;

an n-type semiconductor layer provided at a position farther from the substrate than the p-type semiconductor layer is; and

an active layer provided between the p-type semiconductor layer and the n-type semiconductor layer;

the n-type semiconductor layer being provided with a rectangular n-side electrode whose width in one direction is equal to that of the n-type semiconductor layer,the n-type semiconductor layer having a thickness t that satisfies Formula 1 given below,the semiconductor light emitting element including a side surface extending in a lamination direction and being formed with a plurality of projections,the projections having bottom widths an average W_Aof which satisfies W_A≧

λ

/n when a wavelength of light emitted from the active layer is λ and

index of refraction of one of the n-type semiconductor layer and the p-type semiconductor layer is n,wherein Formula 1 is;

$t \geq \frac{ρ J_{0} e}{4 γ κ_{B} T} \cdot W (L - W)$ where L is width of the n-type semiconductor layer in a direction which is different from said one direction, T is absolute temperature, W is width of the n-side electrode in a direction which is different from said one direction, J₀is current density at a contact portion between the n-side electrode and the n-type semiconductor layer, e is elementary charge, γ

is diode ideality factor, κ

_Bis Boltzmann constant, and ρ

is specific resistance of the n-type semiconductor layer.

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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_Aof widths at bottoms of the projections is set to satisfy W_A≧λ/n.

$\begin{matrix} t \geq \frac{ρ J_{0} e}{4 {γκ}_{B} T} \cdot W (L - W) & Formula 1 \end{matrix}$

- 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,
- J₀is 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_Bis Boltzmann constant,
- ρ is specific resistance of the n-type semiconductor layer.

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10 Claims

1. A semiconductor light emitting element comprising:
- a substrate;
  
  a p-type semiconductor layer supported by the substrate;
  
  an n-type semiconductor layer provided at a position farther from the substrate than the p-type semiconductor layer is; and
  
  an active layer provided between the p-type semiconductor layer and the n-type semiconductor layer;
  
  the n-type semiconductor layer being provided with a rectangular n-side electrode whose width in one direction is equal to that of the n-type semiconductor layer,the n-type semiconductor layer having a thickness t that satisfies Formula 1 given below,the semiconductor light emitting element including a side surface extending in a lamination direction and being formed with a plurality of projections,the projections having bottom widths an average W_Aof which satisfies W_A≧
  
  λ
  
  /n when a wavelength of light emitted from the active layer is λ and
  
  index of refraction of one of the n-type semiconductor layer and the p-type semiconductor layer is n,wherein Formula 1 is;
  
  $t \geq \frac{ρ J_{0} e}{4 γ κ_{B} T} \cdot W (L - W)$ where L is width of the n-type semiconductor layer in a direction which is different from said one direction, T is absolute temperature, W is width of the n-side electrode in a direction which is different from said one direction, J₀is current density at a contact portion between the n-side electrode and the n-type semiconductor layer, e is elementary charge, γ
  
  is diode ideality factor, κ
  
  _Bis Boltzmann constant, and ρ
  
  is specific resistance of the n-type semiconductor layer.

2. 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 formed with a plurality of projections,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_Aof widths at bottoms of the projections satisfies;
  
  W_A≧
  
  λ
  
  /n.
- View Dependent Claims (3, 4)
- - 3. The semiconductor light emitting element according to claim 2, wherein at least one of the n-type semiconductor layer and the p-type semiconductor layer is made of GaN.
  - 4. The semiconductor light emitting element according to claim 2, wherein the projections extend in the lamination direction and are triangular or semicircular in cross section.

5. A semiconductor light emitting element comprising:
- a substrate;
  
  a p-type semiconductor layer supported by the substrate;
  
  an n-type semiconductor layer arranged at a position farther from the substrate than the p-type semiconductor layer is; and
  
  an active layer arranged between the p-type semiconductor layer and the n-type semiconductor layer;
  
  wherein the n-type semiconductor layer is formed with a circular n-side electrode,wherein the n-type semiconductor layer has a thickness t which satisfies Formula 2;
  
  $\begin{matrix} t \geq \frac{ρ J_{0} {e W}^{2}}{8 γ κ_{B} T} \cdot \log (\frac{L}{W}) & Formula 2 \end{matrix}$ where L is representative length of the semiconductor light emitting element, T is absolute temperature, W is diameter of the n-side electrode, J₀is current density at a contact portion between the n-side electrode and the n-type semiconductor layer, e is elementary charge, γ
  
  is diode ideality factor, κ
  
  _Bis Boltzmann constant, and ρ
  
  is specific resistance of the n-type semiconductor layer.
- View Dependent Claims (6, 7)
- - 6. The semiconductor light emitting element according to claim 5, wherein the n-type semiconductor layer is formed with a plurality of projections,wherein the thickness t of the n-type semiconductor layer satisfies Formula 3 instead of Formula 2:
7. The semiconductor light emitting element according to claim 5, wherein the n-type semiconductor layer is made of n-GaN.

8. A semiconductor light emitting element comprising:
- a substrate;
  
  a p-type semiconductor layer supported by the substrate;
  
  an n-type semiconductor layer arranged at a position farther from the substrate than the p-type semiconductor layer is; and
  
  an active layer arranged between the p-type semiconductor layer and the n-type semiconductor layer;
  
  wherein the n-type semiconductor layer is formed with a rectangular n-side electrode whose width in one direction is equal to that of the n-type semiconductor layer,wherein the n-type semiconductor layer has a thickness t which satisfies Formula 4 given below;
  
  $\begin{matrix} t \geq \frac{ρ J_{0} e}{4 γ κ_{B} T} \cdot W (L - W) & Formula 4 \end{matrix}$ where L is width of the n-type semiconductor layer in a direction which is different from said one direction, T is absolute temperature, W is width of the n-side electrode in a direction which is different from said one direction, J₀is current density at a contact portion between the n-side electrode and the n-type semiconductor layer, e is elementary charge, γ
  
  is diode ideality factor, κ
  
  _Bis Boltzmann constant, and ρ
  
  is specific resistance of the n-type semiconductor layer.
- View Dependent Claims (9, 10)
- - 9. The semiconductor light emitting element according to claim 8, wherein the n-type semiconductor layer is formed with a plurality of projections,wherein the thickness t of the n-type semiconductor layer satisfies Formula 5 instead of Formula 4:
10. The semiconductor light emitting element according to claim 8, wherein the n-type semiconductor layer is made of n-GaN.

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Current Assignee
ROHM Co., Ltd.
Original Assignee
ROHM Co., Ltd.
Inventors
Nakahara, Ken, Sakai, Mitsuhiko, Okazaki, Tadahiro

Granted Patent

US 7,781,791 B2
Time in Patent Office

Days
Field of Search
US Class Current

257/88
CPC Class Codes

H01L 33/20   with a particular shape, e....

H01L 33/22   Roughened surfaces, e.g. at...

H01L 33/32   containing nitrogen

Semiconductor Light Emitting Element

First Claim

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Semiconductor Light Emitting Element

First Claim

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Abstract

30 Citations

10 Claims

Specification

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