Multi-section core-shell InGaN/GaN quantum-well nanorod light-emitting diode array

Abstract

The growth of a two-section, core-shell, InGaN/GaN quantum-well (QW) nanorod- (NR-) array light-emitting diode device based on a pulsed growth technique with metalorganic chemical vapor deposition is demonstrated. A two-section n-GaN NR is grown through a tapering process for forming two uniform NR sections of different cross-sectional sizes. The cathodoluminescence (CL), photoluminescence (PL), and electrolumines-cence (EL) characterization results of the two-section NR structure are compared with those of a single-section NR sample, which is prepared under the similar condition to that for the first uniform NR section of the two-section sample. All the CL, PL, and EL spectra of the two-section sample (peaked between 520 and 525 nm) are red-shifted from those of the single-section sample (peaked around 490 nm) by >30 nm in wavelength. Also, the emitted spectral widths of the two-section sample become significantly larger than their counterparts of the single-section sample. The PL spectral full-width at half-maximum increases from ~37 to ~61 nm. Such variations are attributed to the higher indium incorporation in the sidewall QWs of the two-section sample due to the stronger strain relaxation in an NR section of a smaller cross-sectional size and the more constituent atom supply from the larger gap volume between neighboring NRs.

Carrier Dynamics and Electro-Optical Characterization of High-Performance GaN/InGaN Core-Shell Nanowire Light-Emitting Diodes

“…The LED shows a turn-on voltage of 2.9 V and a series resistance of 25 Ω. The combination of a low turn-on voltage and low series resistance places this device among the highest performing of those reported for GaN/InGaN core-shell nanowire-based LEDs in terms of current-voltage characteristics and internal quantum efficiency 36 , 44 , 45 , 77 . With advanced LED packaging techniques unavailable for this work, the light extraction efficiency (EXE) was simulated to enable an estimate of the total output power and external quantum efficiency (EQE) of the device.…”

“…The IQE versus excitation power plot provides important information about the efficiency droop for the nanowire-based LED. Previously, other groups only reported the peak IQE, which ranged from 8% to 58% in various studies 44 , 45 , 77 , 83 . The peak IQE here is 62%, which is among the highest reported for GaN/InGaN core-shell nanowire-based LEDs.…”

“…Although there are numerous reports related to growth techniques for bottom-up core-shell nanowires using SAE, few of these reports demonstrate high-performance electrically-injected nanowire-based LEDs 36 , 44 , 45 , 77 . One of the most significant challenges in obtaining electrically injected devices is achieving efficient p-type doping in the core-shell nanowire LEDs.…”

“…Here we present electrically-injected GaN/InGaN core-shell nanowire-based LEDs with among the highest performance levels reported thus far 36 , 44 , 45 , 77 . We perform a thorough investigation of the optical and electrical characteristics and compare the device performance to previously reported core-shell nanowire LEDs.…”

A Decade of Nonpolar and Semipolar III-Nitrides: A Review of Successes and Challenges

“…However, some recent progress has been made toward increasing the IQE of nanostructure‐based materials. For example, InGaN/GaN core‐shell nanowire‐based LEDs have achieved up to 62% IQE . A significant improvement of the reported IQE from <5% in 2013 to ∼62% in 2018 shows some promises of such nanostructures for future optoelectronic applications.…”