LEDs Based on AlInP Alloys
High Bandgap III-V Alloys for High Efficiency Optoelectronics
There currently exists a gap in the wavelength spectral window from roughly 530 nm to 570 nm, known as the “green gap,” where realization of efficient green LEDs is proving to be very difficult. Current white light generation techniques rely on color mixing from red, blue and green light. While reasonable red and blue LEDs are available for this scheme, availability of a good green LED poses a significant technological challenge.
For over a decade, wide bandgap III-V alloys that utilize Ga, Al and In as cations, and N as the anion, have been extensively researched for synthesis of various wavelength LEDs, including green LEDs. The primary obstacle for green LEDs is the poor material quality due to the alloy phase separation that occurs when substantial amounts of In is added to GaN to shift the emission into the green gap, or substantial amounts of Ga is added to the InN to shift the emission towards the red.
DescriptionThe present invention provides a solution to this problem by using AlInP which undergoes a transition from a direct to indirect gap semiconductor at the highest energy of any of the non-nitride III-V alloys. Green wavelength emission can be achieved at alloy compositions several kT away from indirect bandgap, preventing efficiency loss through intervalley transfer of carriers.Benefits
- GaAs or Ge substrates can be used instead of expensive GaN or SiC substrates
- Direct bandgap of AlInP also spans yellow, orange and red wavelength emission ranges
- Shorter wavelength emission also possible, enabling multiple wavelength emission from the same device
- Technique can be applied to all variants of LED designs
|Technology ID||Development Stage||Availability||Published||Last Updated|
|NREL ROI 10-64||Development||Available||07/18/2011||07/18/2011|