Design and demonstration of ultra-wide bandgap AlGaN tunnel junctions

Ultra violet light emitting diodes (UV LEDs) face critical limitations in both the injection efficiency and the light extraction efficiency due to the resistive and absorbing p-type contact layers. In this work, we investigate the design and application of polarization engineered tunnel junctions fo...

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Bibliographic Details
Published in:Applied physics letters 2016-09, Vol.109 (12)
Main Authors: Zhang, Yuewei, Krishnamoorthy, Sriram, Akyol, Fatih, Allerman, Andrew A., Moseley, Michael W., Armstrong, Andrew M., Rajan, Siddharth
Format: Article
Language:English
Subjects:
Applied physics
Composition
CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
Design engineering
Emitters
Energy gap
ENGINEERING
III-V semiconductors
Light emitting diodes
Low resistance
Low voltage
Organic light emitting diodes
Polarization
Tunnel junctions
tunneling
ultraviolet light
Ultrawideband
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Summary:Ultra violet light emitting diodes (UV LEDs) face critical limitations in both the injection efficiency and the light extraction efficiency due to the resistive and absorbing p-type contact layers. In this work, we investigate the design and application of polarization engineered tunnel junctions for ultra-wide bandgap AlGaN (Al mole fraction >50%) materials towards highly efficient UV LEDs. We demonstrate that polarization-induced three dimensional charge is beneficial in reducing tunneling barriers especially for high composition AlGaN tunnel junctions. The design of graded tunnel junction structures could lead to low tunneling resistance below 10−3 Ω cm2 and low voltage consumption below 1 V (at 1 kA/cm2) for high composition AlGaN tunnel junctions. Experimental demonstration of 292 nm emission was achieved through non-equilibrium hole injection into wide bandgap materials with bandgap energy larger than 4.7 eV, and detailed modeling of tunnel junctions shows that they can be engineered to have low resistance and can enable efficient emitters in the UV-C wavelength range.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4962900