Abstract
InGaN/GaN nanorod light-emitting diode (LED) arrays were fabricated using nanoimprint and reactive ion etching. The diameters of the nanorods range from 120 to 300 nm. The integral photoluminescence (PL) intensity for 120 nm nanorod LED array is enhanced as 13 times compared to that of the planar one. In angular-resolved PL (ARPL) measurements, there are some strong lobes as resonant regime appeared in the far-field radiation patterns of small size nanorod array, in which the PL spectra are sharp and intense. The PL lifetime for resonant regime is 0.088 ns, which is 40 % lower than that of non-resonant regime for 120 nm nanorod LED array. At last, three dimension finite difference time domain (FDTD) simulation is performed. The effects of guided modes coupling in nanocavity and extraction by photonic crystals are explored.
Highlights
Nanoscale light-emitting devices have attracted much attention for their potential applications in biotechnology [1, 2], communication [3] and solid state lighting [4, 5]
The improvement of internal quantum efficiency (IQE) is reasonable for nanorod light-emitting diode (LED), because of the strain relaxation [6,7,8,9] and extra in-plane excitonic confinement [7, 10] in InGaN active layer
The surface potential of the multiple quantum wells (MQWs) layer drops monotonously from p-GaN to n-GaN [28], which leads to gradual neck shaped MQWs layers for these nanorods
Summary
Nanoscale light-emitting devices have attracted much attention for their potential applications in biotechnology [1, 2], communication [3] and solid state lighting [4, 5]. Compared to planar light-emitting diodes (LEDs), nanorod LEDs show high performances with higher internal quantum efficiency (IQE), higher light extraction efficiency (LEE) and optimal directionality [4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20]. The emission intensity of nanorod array is improved by an order of magnitude or more, which is mainly due to the reduction of modified guided modes [13,14,15]. Three key mechanisms are suggested for the high efficiency: guided modes reduction, embedded quantum wells (QWs) and ultra-efficient out-coupling of fundamental
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