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(a) Schematic and (b) 45° tilted scanning electron microscopy image of InGaN/GaN disks-in-nanowires grown on (001) Si substrate. Inset to (b) shows high resolution transmission electron microscopy image of InGaN disks in a single GaN nanowire.
Temperature dependent photoluminescence measurements: (a) PL spectra of as-grown and passivated disk-in-nanowire samples measured at 10 and 300 K with 405 nm excitation. Inset shows the variation of PL peak intensity with excitation power density in a parylene passivated sample at 10 and 300 K; (b) PL spectra from a parylene passivated sample at 10 and 300 K measured with 267 nm excitation. The shoulder at ∼720 nm is probably from defect-related recombination; (c) measured variation of PL peak energy with temperature at three different points in a parylene passivated DNW sample with excitation at 405 nm. The solid line is the calculated In0.54Ga0.46N bandgap shift with temperature according to the Varshni equation using α = 9.39 × 10−4 eV K−1 and β = 772 K.
Variation of radiative, non-radiative, and total carrier lifetime with temperature in (a) as-grown, (b) parylene passivated disks-in-nanowires. The inset in (a) shows a typical TRPL transient of an as-grown sample measured at 300 K with 405 nm excitation. The solid curve is calculated with the stretched exponential model.
Characteristics of disk-in-nanowire LED on silicon with parylene passivation: (a) schematic representation; (b) measured current-voltage characteristics. Inset shows injection current dependent electroluminescence spectra measured atroom temperature; (c) light-current characteristics measured with pulsed bias. Inset shows the corresponding variation of external quantum efficiency with injection current density.
Carrier lifetimes in as-grown and passivated red-emitting InGaN/GaN disks-in-nanowires at T = 300 K. The measurements were carried out with 405 nm excitation.
Carrier lifetimes in as-grown and passivated GaN region of the nanowire at T = 300 K with 267 nm excitation.
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