Accession Number:

ADA505915

Title:

Improved UV Nitride Light Emitting Diode With Engineered Spontaneous and Piezoelectric Charges

Descriptive Note:

Conference paper

Corporate Author:

ARMY RESEARCH LAB ADELPHI MD

Personal Author(s):

• Shen, Paul H.
• Reed, Meredith L.
• Readinger, Eric D.
• Wraback, Michael

Report Date:

2008-12-01

Pagination or Media Count:

8.0

Abstract:

Most III-V nitride light emitting diodes have an n-type down structure with Ga polarity. In such a device, the active layer is grown on top of the n-cladding layer and the p-type cladding layer is grown on top of the active layer. We have analyzed the band structure of such a device and found a reduced effective conduction band barrier due to the positive spontaneous and piezoelectric polarization charge, resulting in large electron overshoot and necessitating the introduction of the commonly employed electron blocking layer. On the other hand, the polarization charge at the corresponding interface for a p-type down device with Ga polarity is negative, resulting in a significant enhancement of the electron barrier and the existence of a 2D hole gas near the interface. These are beneficial to the performance of single heterojunction LEDs. We have fabricated and tested such a device with a peak efficiency above 100Asq cm and only approx. 10 droop up to 500Asq cm, which was achieved without the implementation of an AlGaN electron-blocking layer or a second hetero-interface.

Descriptors:

• *ELECTRIC CHARGE
• *LIGHT EMITTING DIODES
• *CLADDING
• *PIEZOELECTRIC MATERIALS
• *N TYPE SEMICONDUCTORS
• POLARITY
• P TYPE SEMICONDUCTORS
• ELECTRONS
• NITRIDES
• HETEROJUNCTIONS
• POLARIZATION
• PEAK VALUES
• GALLIUM

Subject Categories:

• Electrical and Electronic Equipment
• Electrooptical and Optoelectronic Devices
• Electricity and Magnetism

Distribution Statement:

APPROVED FOR PUBLIC RELEASE