Transparent electrode

• US 7,948,003 B2
• Filed: 07/21/2008
• Issued: 05/24/2011
• Est. Priority Date: 02/25/2003
• Status: Expired due to Fees

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Nakahara, Ken
• Primary Examiner(s): Such; Matthew W
• Assistant Examiner(s): Naraghi; Ali
• Application Number:
  US12/177,090
• Publication Number:
  US 20080283863A1
• Time in Patent Office: 1,037 Days
• Field of Search: 257/43, 257 79-103
• US Class Current: 257/99
• CPC Class Codes: H01L 33/42 Transparent materials

Abstract

In order to emit a light from an electrode side, in semiconductor light emitting devices such as LED and the like, and liquid crystal, the electrode is formed of a transparent material so as to transmit a light through the transparent electrode and exit the light. A ZnO, which constitutes a material for the transparent electrode, is subject to erosion by acid and alkali, thus, as the case may cause loss of a reliability of the electrode under the influence of ion-containing moisture. In order to solve such a problem, this invention has as its aim a transparent electrode film provided with stability capable of preventing any degradation under the influence of any ion-containing moisture, while being kept acid-proof and alkali-proof. In order to accomplish the above-mentioned aim, this invention provides a transparent electrode made up of a ZnO as its main material, wherein its surface is covered with a Mg-doped ZnO film.

Claims

1. A transparent electrode comprising:

a fundamental electrode comprising ZnO formed on a semiconductor layer; and

an Mg-doped ZnO film formed on the fundamental electrode,

wherein the Mg-doped ZnO film overlies an upper surface and side surfaces of the fundamental electrode.

2. The transparent electrode of claim 1, wherein the semiconductor layer comprises a GaN system semiconductor layer.

3. The transparent electrode of claim 1, wherein the semiconductor layer comprises an n-type GaN system semiconductor layer formed on a substrate, an emission layer formed on the n-type GaN system semiconductor layer, and a p-type GaN system semiconductor layer formed on the emission layer.

4. The transparent electrode of claim 1, wherein a first metal pattern is formed on the Mg-doped ZnO film.

5. The transparent electrode of claim 1, wherein a second metal pattern is formed on the semiconductor layer.

6. The transparent electrode of claim 1, wherein the Mg-doped ZnO film improves acid resistance of the transparent electrodes.

7. The transparent electrode of claim 1, wherein doping Mg is 12 mol % or more in the Mg-doped ZnO film.

8. The transparent electrode of claim 1, wherein the Mg-doped ZnO film is formed with a sputtering method, an ion plating method or an evaporation method.

9. A light emitting device comprising:

a semiconductor layer formed on a substrate;

a fundamental electrode comprising ZnO formed on the semiconductor layer; and

an Mg-doped ZnO film formed on the fundamental electrode,

wherein the Mg-doped ZnO film overlies an upper surface and side surface of the fundamental electrode formed on the semiconductor layer.

10. The light emitting device of claim 9, wherein the semiconductor layer comprises a GaN system semiconductor layer.

11. The light emitting device of claim 9, wherein the semiconductor layer comprises an n-type GaN system semiconductor layer formed on a substrate, an emission layer formed on the n-type GaN system semiconductor layer, and a p-type GaN system semiconductor layer formed on the emission layer.

12. The light emitting device of claim 9, wherein a first metal pattern is formed on the Mg-doped ZnO film.

13. The light emitting device of claim 9, wherein a second metal pattern is formed on the semiconductor layer.

14. The light emitting device of claim 9, wherein the Mg-doped ZnO film improves acid resistance of the light emitting device.

15. The light emitting device of claim 9, wherein doping Mg is 12 or more in the Mg-doped ZnO film.

16. The light emitting device of claim 9, wherein the Mg-doped ZnO film is formed with a sputtering method, an ion plating method or an evaporation method.