Coaxial In_xGa_1–xN/GaN Multiple Quantum Well Nanowire Arrays on Si(111) Substrate for High-Performance Light-Emitting Diodes

Abstract

We report the growth of high-quality nonpolar (m-plane) and semipolar (r-plane) multiple quantum well (MQW) nanowires (NWs) for high internal quantum efficiency light emitting diodes (LEDs) without polarization. Highly aligned and uniform In(x)Ga(1-x)N/GaN MQW layers are grown coaxially on the {1-100} sidewalls of hexagonal c-axis n-GaN NWs on Si(111) substrates by a pulsed flow metal-organic chemical vapor deposition (MOCVD) technique. The photoluminescence (PL) measurements reveal that the wavelength and intensity of an MQW structure with various pairs (2-20) are very stable and possess composition-dependent emission ranging from 369 to 600 nm. The cathodoluminescence (CL) spectrum of individual In(x)Ga(1-x)N/GaN MQW NW is dominated by band-edge emission at 369 and 440 nm with a relatively homogeneous profile of parallel alignment. High-resolution transmission electron microscopy (HR-TEM) studies of coaxial InxGa1-xN/GaN MQW NWs measured along the [0001] and [2-1-10] zone axes reveal that the grown NWs are uniform with six nonpolar m-plane facets without any dislocations and stacking faults. The p-GaN/In(x)Ga(1-x)N/GaN MQW/n-GaN NW coaxial LEDs show a current rectification with a sharp onset voltage at 2.65 V in the forward bias. The linear enhancement of power output could be attributed to the elimination of piezoelectric fields in the In(x)Ga(1-x)N/GaN MQW active region. The superior performance of coaxial NW LEDs is observed in comparison with that of thin film LEDs. Overall, the feasibility of obtaining low defect and strain free m-plane coaxial NWs using pulsed MOCVD can be utilized for the realization of high-power LEDs without an efficiency droop. These kinds of coaxial NWs are viable high surface area MQW structures which can be used to enhance the efficiency of LEDs.

Variable‐Color Light‐Emitting Diodes Using GaN Microdonut arrays

“…The effi ciency of microdonut LEDs is comparable to or several times higher than those of micropyramid and microrod LEDs. [ 11,12 ] Although the internal quantum effi ciency of the GaN microdonut structures is comparable to or even higher than that of the thin fi lm structures, [ 13 ] the wall plug effi ciency of the microstructure and nanostructure LEDs is much lower than those of commercialized thin fi lm LEDs. We believe that the LED effi ciency could be signifi cantly increased by optimizing the materials growth and device fabrication process parameters.…”

Regularly patterned non-polar InGaN/GaN quantum-well nanorod light-emitting diode array

“…Nitride nanorods (NRs) with randomly distributed and regularly patterned structures have been grown with molecular beam epitaxy (MBE) [1][2][3][4] and metalorganic chemical vapor deposition (MOCVD) [5][6][7][8] for improving the crystal quality. On an NR oriented along the caxis, non-polar InGaN/GaN quantum wells (QWs) on the sidewall m-planes [9,10], semipolar QWs on the slant-facet {1-101}-planes [11], and polar QWs on the cross-sectional cplane [4,5] have been formed for fabricating light-emitting diodes (LEDs).…”

Hydrogen Generation using non-polar coaxial InGaN/GaN Multiple Quantum Well Structure Formed on Hollow n-GaN Nanowires

“…When photosensitivity39 (I P /I dark ) was recorded against applied bias at different wavelengths, photosensitivity values were found much higher for InGaN/GaN MQWs grown on hollow n-GaN NWs (Fig. 6c) compared to the wells grown on solid n-GaN NWs (Fig.…”