News: LEDs
30 September 2024
Lumileds demonstrates InGaN-based deep red LEDs with 7.5% wall-plug efficiency
LED product and lighting maker Lumileds LLC of San Jose, CA, USA claims to be first to demonstrate that rich deep red light (615nm dominant wavelength corresponding with 635nm peak) can be produced with indium gallium nitride (InGaN) LEDs, achieving a wall-plug efficiency of 7.5% at a current density of 10A/cm2. The firm says that its breakthroughs address the challenges associated with high indium concentrations, including spectral peak shifts and broadening with current density.
The InGaN material system is an attractive alternative to aluminium indium gallium phosphide (AlInGaP) for creating red light sources because it harmonizes manufacturing with green and blue LEDs, which are also based on InGaN. The large industrial capacity of InGaN gives economies of scale and is preferred for integration with silicon semiconductor manufacturing. InGaN red is especially promising for micro-LED applications because of its characteristic of maintaining efficiency at micron-scale sizes and low current density.
“The current efficiency for sub-10μm red micro-LEDs is an impediment to cost-effective and efficient micro-LED displays,” notes Rob Armitage, director of nitride epitaxy development. “Our work on red InGaN validates our roadmap to meeting cost and efficiency thresholds for adoption.”
In addition to demonstrating high-efficiency red InGaN, Lumileds has established red, green and blue light emission from a single InGaN epitaxial stack. Subsequently, the firm translated this into micro-LEDs with what is claimed to be excellent color quality and electrical characteristics. Integration of the three primary colors into single micro-LEDs has a tremendous impact on achieving low-cost high-yield micro-LED display assembly and will ultimately enable compact full-color displays for augmented-reality (AR) applications, says Lumileds.
Armitage is an invited speaker at the 12th International Workshop on Nitride Semiconductors (IWN 2024) in Honolulu, Hawaii (3–8 November), where he will discuss the development of InGaN LEDs for color display applications.
