Strain relaxation in InGaN/GaN micro-pillars evidenced by high resolution cathodoluminescence hyperspectral imaging

Abstract

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Microcathodoluminescence spectra evolution for planar and nanopillar multiquantum-well GaN-based structures as a function of electron irradiation dose

“…This is indeed happening in many MCL experiments. [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] For InGaN/GaN multiple quantum well (MQW) LED structures, the effects of low energy electron beam irradiation (LEEBI) on optical properties, as detected by MCL, were studied in Refs. 6, 10, and 13-17.…”

Monolithic Broadband InGaN Light-Emitting Diode

“…This is consistent with the postulations that strain relaxation only occurs at the surface regions of nanostructures. [(15), (16), (17)] The PL peak wavelength at t1 still exhibits power-dependent blue-shifts. In terms of photon energies, the linewidth broadening from 2.5 kW/cm 2 to 46 kW/cm 2 is ~10meV, which is relatively small compared to the corresponding peak shift of ~60meV.…”

“…Such strain-induced piezoelectric field reduces the effective bandgap energy leading to a red-shift of the emission spectrum, a phenomenon known as the quantum-confined Stark effect (QSCE), [(14)] which can be partially relieved by releasing the strain through nanoscale structuring of the QWs. [(15), (16), (17) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 Figure 1. a) Schematic diagram of the proposed monolithic phosphor-free structure comprising arrays of nanostructures of different dimensions. Broadband emission by way of combining monochromatic emissions of different center wavelengths from the differentlysized nanostructures is possible due to their different extents of strain-relaxation from the asgrown wafer.…”

Temperature Dependence of Low‐Energy Electron Beam Irradiation Effect on Optical Properties of MQW InGaN/GaN Structures

“…As shown in Refs. under nanopillar formation by dry etching the strain relaxation took place that allowed to assume that the effects observed under LEEBI are also determined by the strain relaxation in local regions of MQWs. It should be also mentioned that in GaN nanorods the strain relaxation under LEEBI was observed in Ref.…”