Green-Emitting $(\lambda=525~{\rm nm})$ InGaN/GaN Quantum Dot Light Emitting Diodes Grown on Quantum Dot Dislocation Filters

Abstract

We have investigated the dislocation filtering characteristics of InGaN/GaN quantum dot multilayers grown at the substrate/active layer interface along the c-axis. Etch pit dislocation density measurements reveal a reduction in defect density by a factor of 5, from ~ 5×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> to ~ 9.8×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sup> cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> in a GaN overlayer with an optimized quantum dot multilayer. This is accompanied by a reduction of electron and hole trap densities in the GaN layer by a factor of 3 and an increase in the luminescence efficiency of green-emitting In0.35Ga0.65N/GaN quantum dots grown atop such filters. Green-emitting (λ = 525 nm) quantum dot light emitting diodes having optimized dislocation filter show marked improvement in their current-voltage and light-current characteristics and in their external quantum efficiency. The peak efficiency is achieved at an injection level of 27 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .