Optimal ITO transparent conductive layers for InGaN-based amber/red light-emitting diodes
Optics Express
|May 15, 2020
Summary
Optimized indium tin oxide (ITO) fabrication using radiofrequency sputtering and annealing significantly reduced sheet resistivity and improved transmittance for InGaN-based amber/red light-emitting diodes (LEDs). This enhanced LED light output power by over 15%.
Area of Science:
- Materials Science
- Optoelectronics
- Semiconductor Physics
Background:
- Indium tin oxide (ITO) is a crucial transparent conductive material for light-emitting diodes (LEDs).
- Optimizing ITO fabrication is essential for improving the performance of InGaN-based LEDs, particularly in the amber and red spectrum.
- Existing ITO fabrication methods may not achieve optimal electrical and optical properties for specific LED applications.
Purpose of the Study:
- To optimize the fabrication of indium tin oxide (ITO) for InGaN-based amber and red light-emitting diodes (LEDs).
- To achieve low sheet resistivity and high transmittance in the visible spectrum for ITO films.
- To improve the light output power of amber and red LEDs through enhanced ITO contact layers.
Main Methods:
- Utilized radiofrequency sputtering to deposit ITO films, optimizing for low-pressure conditions.
- Implemented a two-step annealing process to further reduce sheet resistivity and enhance optical properties.
- Investigated the formation of ohmic contacts using double ITO layers deposited by sputtering onto p-GaN.
- Compared the performance of LEDs fabricated with sputtered ITO layers against those using e-beam evaporated ITO.
Main Results:
- Achieved a low sheet resistivity below 2×10-4 Ωcm for ITO films.
- Obtained high transmittance exceeding 98% in the 590 nm to 780 nm wavelength range.
- Demonstrated that double ITO layers formed excellent ohmic contact with p-GaN.
- Observed significant enhancements in light output power: 15.6% for amber LEDs and 13.0% for red LEDs.
Conclusions:
- The optimized radiofrequency sputtering and two-step annealing process effectively improves ITO properties for InGaN-based LEDs.
- The double ITO layer approach provides superior ohmic contact and enhances light extraction efficiency.
- This fabrication method offers a significant performance improvement for amber and red LEDs, paving the way for more efficient optoelectronic devices.
