Investigation of Photonic-Crystal-Structured p-GaN Nanorods Fabricated by Polystyrene Nanosphere Lithography Method to Improve the Light Extraction Efficiency of InGaN/GaN Green Light-Emitting Diodes

Abstract

We fabricated the photonic-crystal-structured p-GaN (PC-structured p-GaN) nanorods using the modified polystyrene nanosphere (PS NS) lithography method for InGaN/GaN green light-emitting diodes (LEDs) to enhance the light extraction efficiency (LEE). A modified PS NS lithography method including two-times spin-coating processes and the post-spin-coating heating treatment was used to obtain a self-assembly close-packed PS NS array of monolayer as a mask and then a partially dry etching process was applied to PS NS, SiO2, and p-GaN to form PC-structured p-GaN nanorods on the InGaN/GaN green LEDs. The light output intensity and LEE of InGaN/GaN green LEDs with the PC-structured p-GaN nanorods depend on the period, diameter, and height of PC-structured p-GaN nanorods. RSoft FullWAVE software based on the three-dimension finite-difference time-domain (FDTD) algorithm was used to calculate the LEE of InGaN/GaN green LEDs with PC-structured p-GaN nanorods of the varied period, diameter, and height. The optimal period, diameter, and height of PC-structured p-GaN nanorods are 150, 350, and 110 nm. The InGaN/GaN green LEDs with optimal PC-structured p-GaN nanorods exhibit an enhancement of 41% of emission intensity under the driving current of 20 mA as compared to conventional LED.

Design of photonic crystals for light‐emitting diodes

“…Lei et al designed and investigated p-GaN nanorods with photonic crystal structures for InGaN/GaN green LEDs, which were prepared using a modified polystyrene nanosphere (PS-NS) photolithography method to achieve an increase in LEE and LOP. 71 As shown in Figure 11A As can be seen from Figure 11B,C, when PC nanorods with 150, 350, and 110 nm periods, diameters, and heights were used, the LEE of the LEDs was improved by 41%. Liu et al proposed using SiO 2 PC to enhance LED's LEE by investigating the effect of depth, fill factor, and radius of SiO 2 PC on the enhancement of LEE.…”

“…Lei et al. designed and investigated p‐GaN nanorods with photonic crystal structures for InGaN/GaN green LEDs, which were prepared using a modified polystyrene nanosphere (PS‐NS) photolithography method to achieve an increase in LEE and LOP 71 . As shown in Figure 11A, Lei et al.…”

“…L – I – V of InGaN/GaN‐based green light‐emitting diodes (GLEDs) with/without photonic crystal (PhC) structure as a function of (B) PhC structure period and (c) height. Reproduced from ref 71. with permission of MDPI.…”

Advances in lithographic techniques for precision nanostructure fabrication in biomedical applications

“…Lei et al also used polystyrene nanospheres to design gallium nitride (GaN) nanorods for indium gallium nitride/gallium nitride (InGaN/GaN) light-emitting diodes (LEDs). NSL enabled the production of low-cost nanostructures on large, uniform substrates to generate InGaN/GaN LEDs, with an improved light extraction efficiency, for applications in areas such as optics and underwater communications [ 224 ]. Kim et al [ 225 ] developed surfaces featuring nanowell arrays to facilitate neuronal cell growth, while Purwidyantri et al [ 226 ] created gold nanohole arrays to enhance the electrochemical performance of DNA biosensors.…”