Staggered InGaN quantum wells improve LEDs

Staggered indium gallium nitride (InGaN) quantum wells (QWs) can be used to enhance the radiative efficiency of visible-wavelength light-emitting diodes (LEDs), according to researchers at Lehigh University (Bethlehem, PA). Staggered InGaN QW LED structures grown by metal-organic chemical-vapor deposition exhibited 11.2 times more output power than conventional InGaN QW LEDs at a current of 100 mA and a peak wavelength of 455 to 465 nm.

The staggered QW structures consisted of four periods of 12 Å In_0.25Ga_0.75N/12 Å In_0.15Ga_0.85N layers and four periods of 27 Å conventional In_0.21Ga_0.79N forming the active regions of each LED. The measured output power is greater than that predicted by modeling, possibly because of pronounced carrier screening and increased electron-hole wave-function overlap. Other similarly staggered InGaN QW active regions demonstrated improvement in peak photoluminescence by a factor of 4.74 over conventional structures emitting at peak wavelengths from 420 to 430 nm and 500 to 505 nm. Such enhancements of the overlap in InGaN-based active regions can help improve LED efficiency and the lasing threshold of nitride-based lasers. Contact Nelson Tansu at [email protected].