Gallium nitride-based semiconductor element, optical device using the same, and image display apparatus using optical device

• US 8,946,764 B2
• Filed: 06/12/2008
• Issued: 02/03/2015
• Est. Priority Date: 07/03/2007
• Status: Expired due to Fees

• Current Assignee: Sony Semiconductor Solutions Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Biwa, Goshi, Nishinaka, Ippei, Okuyama, Hiroyuki
• Primary Examiner(s): TORNOW, MARK W
• Application Number:
  US12/138,250
• Publication Number:
  US 20090008648A1
• Time in Patent Office: 2,427 Days
• Field of Search: 257/78, 257/86, 257/88, 257/101, 257/102
• US Class Current: 257/102
• CPC Class Codes: H01L 2224/0603 Bonding areas having different sizes, e.g. different heights or widths
• CPC Class Codes: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 27/156 two-dimensional arrays
• CPC Class Codes: H01L 31/0304 including, apart from doping materials or other impurities, only AIIIBV compounds
• CPC Class Codes: H01L 33/025 Physical imperfections, e.g. particular concentration or distribution of impurities
• CPC Class Codes: H01L 33/32 containing nitrogen

Abstract

A GaN-based semiconductor element which can suppress a leakage current generated during reverse bias application, an optical device using the same, and an image display apparatus using the optical device are provided. The GaN-based semiconductor element has a first GaN-based compound layer including an n-type conductive layer; a second GaN-based compound layer including a p-type conductive layer; and an active layer provided between the first GaN-based compound layer and the second GaN-based compound layer. In this GaN-based semiconductor element, the first GaN-based compound layer includes an underlayer having an n-type impurity concentration in the range of 3×10¹⁸ to 3×10¹⁹/cm³, and when a reverse bias of 5 V is applied, a leakage current density, which is the density of a current flowing per unit area of the active layer, is 2×10⁻⁵ A/cm² or less.

Claims

1. A gallium nitride-based semiconductor element comprising:

a first GaN-based compound layer comprising;

a first undoped GaN layer,

an n-type conductive first GaN-based compound semiconductor layer formed on the undoped GaN layer,

an underlayer formed directly on the n-type conductive first GaN-based compound semiconductor layer, and

a second undoped GaN layer formed directly on the underlayer;

an active layer formed on the second undoped GaN layer; and

a second GaN-based compound layer including a p-type conductive layer formed on the active layer such that the active layer is provided between the first GaN-based compound layer and the second GaN-based compound layer,

wherein the underlayer has an n-type impurity concentration in the range of 3×

10¹⁸ to 3×

10¹⁹/cm³, and when a reverse bias of 5 V is applied, a leakage current density, which is the density of a current flowing per unit area of the active layer, is 2×

10<sup>−

5</sup> A/cm² or less.

2. The gallium nitride-based semiconductor element according to claim 1, wherein the n-type impurity concentration of the underlayer is 4×

10¹⁸/cm³ or more, and the leakage current density is 8×

10<sup>−

6</sup> A/cm² or less.

3. The gallium nitride-based semiconductor element according to claim 1, wherein the n-type impurity concentration of the underlayer is 8×

10¹⁸/cm³ or more, and the leakage current density is 1×

10<sup>−

6</sup> A/cm² or less.

4. The gallium nitride-based semiconductor element according to claim 1, wherein the n-type impurity concentration of the underlayer is 1×

10¹⁹/cm³ or more, and the leakage current density is 6×

10<sup>−

7</sup> A/cm² or less.

5. The gallium nitride-based semiconductor element according to claim 1, wherein the underlayer and the active layer each include a GaN-based compound containing In, the atomic composition ratio of In to the sum of In and Ga (In +Ga) in the GaN-based compound forming the underlayer is 0.005 or more and is lower than that of the GaN-based compound forming the active layer.

6. The gallium nitride-based semiconductor element according to claim 1, wherein the underlayer has a thickness in the range of 5 nm to 5 μ

m.

7. The gallium nitride-based semiconductor element according to claim 1, wherein the underlayer has a thickness in the range of 20 nm to 1 μ

m.

8. The gallium nitride-based semiconductor element according to claim 1, wherein the second GaN-based compound layer includes a GaN layer doped with a p-type impurity and having a thickness of 100 nm or more.

9. The gallium nitride-based semiconductor element according to claim 1, wherein the gallium nitride-based semiconductor element is a light-emitting element.

10. An optical device comprising:

a plurality of gallium nitride-based semiconductor elements, each of which is the gallium nitride-based semiconductor element according to claim 1, arranged in a two-dimensional matrix,

wherein first electrodes of the gallium nitride-based semiconductor elements disposed along lines in a first direction are connected to common wires of the respective lines in the first direction, and

second electrodes of the gallium nitride-based semiconductor elements disposed along lines in a second direction are connected to common wires of the respective lines in the second direction.

11. An image display apparatus comprising:

a pixel portion including the optical device according to claim 10,

wherein the gallium nitride-based semiconductor elements are passive matrix driven.

12. The gallium nitride-based semiconductor element according to claim 1, wherein the layers forming the first GaN-based compound layer and the second GaN-based compound layer are transparent to emission light wavelengths.

13. The gallium nitride-based semiconductor element according to claim 1, wherein the n-type conductive first GaN-based compound semiconductor layer forms a contact with an n-type electrode.