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).

Nov 1st, 2007

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 In0.25Ga0.75N/12 Å In0.15Ga0.85N layers and four periods of 27 Å conventional In0.21Ga0.79N 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 tansu@lehigh.edu.

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