Influence of stress on optical transitions in GaN nanorods containing a single InGaN/GaN quantum disk

Abstract

Articles you may be interested inCross-sectional sizes and emission wavelengths of regularly patterned GaN and core-shell InGaN/GaN quantum-well nanorod arrays J. Appl. Phys. 113, 054315 (2013) Cathodoluminescence (CL) hyperspectral imaging has been performed on GaN nanorods containing a single InGaN quantum disk (SQD) with controlled variations in excitation conditions. Two different nanorod diameters (200 and 280 nm) have been considered. Systematic changes in the CL spectra from the SQD were observed as the accelerating voltage of the electron beam and its position of incidence are varied. It is shown that the dominant optical transition in the SQD varies across the nanorod as a result of interplay between the contributions of the deformation potential and the quantum-confined Stark effect to the transition energy as consequence of radial variation in the pseudomorphic strain. V C 2014 AIP Publishing LLC.

The effects of nanocavity and photonic crystal in InGaN/GaN nanorod LED arrays

“…Especially the blue shift is about 7 nm for 120 nm nanorod array. Strain relaxation of nanorods was confirmed in many reports [ 6 – 8 , 10 , 14 , 21 ]. It will improve the overlaps of the electron and hole wave function, and reduce the coupling between LO-phonon and exciton [ 31 ].…”

“…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 – 20 ]. The improvement of IQE is reasonable for nanorod LEDs, because of the strain relaxation [ 6 – 9 ] and extra in-plane excitonic confinement [ 7 , 10 ] in InGaN active layer. Moreover, the nanocavity effect is confirmed to enhance the spontaneous emission (SpE) rate in well-ordered nanostructures [ 11 , 12 ].…”

Nano-Cathodoluminescence Measurement of Asymmetric Carrier Trapping and Radiative Recombination in GaN and InGaN Quantum Disks

“…This diffusive asymmetry of the majority carriers explains why CL intensity decreases at a faster rate on the right side of the quantum well than it increased on the left. The asymmetry seen in peak intensity for this AlN/GaN heterostructures is consistent with a previous report of intensity across a well (Tizei et al, 2014) and a scanning electron microscope-based CL experiment with an InGaN well in a GaN nanorad (Zhuang et al, 2014). This has also been observed in InGaN quantum dots within GaN using a STEM-CL setup, although without a clear physical explanation of the observed asymmetry (Tourbot et al, 2012).…”

Monolithic InGaN Multicolor Light‐Emitting Devices

“…This allows the strain in the quantum wells to relax toward the edges, which reduces the polarization fields and thus the extent of QCSE. [22,23] As a result, the quantum well band profile becomes less triangular, causing an increase in the effective bandgap energy without changing the indium content of the quantum wells, which results in blue-shifted emission spectra. [22][23][24][25][26][27][28][29][30][31] There is also an increase in the internal quantum efficiency (IQE), as the electron-hole wavefunction overlap increases.…”

“…[22,23] As a result, the quantum well band profile becomes less triangular, causing an increase in the effective bandgap energy without changing the indium content of the quantum wells, which results in blue-shifted emission spectra. [22][23][24][25][26][27][28][29][30][31] There is also an increase in the internal quantum efficiency (IQE), as the electron-hole wavefunction overlap increases. [32] Moreover, as the size of nanostructures decreases, a larger portion of the nanostructures falls within the region 10 nm from the edge, where the strain relaxation (especially in the quantum wells) is strongest, [31] hence, the degree of strain relaxation in the nanostructure increases giving rise to greater spectral blue shift.…”