Transparent electrode design for AlGaN deep-ultraviolet light-emitting diodes
Optics Express
|December 17, 2017
Summary
Zinc gallate (ZnGa2O4) thin films enhance deep-ultraviolet LEDs. These films improve light output power and current spreading in novel LED designs, boosting performance.
Area of Science:
- Materials Science
- Optoelectronics
- Semiconductor Physics
Background:
- Deep-ultraviolet (DUV) light-emitting diodes (LEDs) require efficient p-type transparent contact layers.
- Traditional indium tin oxide (ITO) layers face limitations in DUV applications.
Purpose of the Study:
- To investigate the use of zinc gallate (ZnGa2O4; ZGO) thin films as a p-type transparent contact layer in DUV AlGaN-based LEDs.
- To enhance the light output power and current spreading of DUV LEDs.
Main Methods:
- Fabrication of ZGO thin films with high transmittance in the DUV range (92.3% at 280 nm).
- Implementation of two ohmic contact structures: ZGO/dot-ITO/LED (D-LED) and ZGO/ITO/LED (W-LED).
- Comparison of device performance with a conventional ITO-LED (C-LED) at an injection current of 20 mA.
Main Results:
- Both D-LED and W-LED structures showed improved light output power and current spreading compared to C-LED.
- The D-LED exhibited a significant 33.7% enhancement in light output power, while the W-LED showed a 12.3% enhancement.
- Enhanced performance is attributed to improved current spreading and light-extracting efficiency from the ZGO/dot-ITO integration.
Conclusions:
- Zinc gallate (ZGO) is a promising material for p-type transparent contact layers in DUV LEDs.
- The novel D-LED structure incorporating ZGO/dot-ITO offers substantial improvements in LED performance.
- ZGO integration effectively addresses challenges in current spreading and light extraction for DUV LED applications.
