The quantum-confined Stark effect in InAs/In(Ga)As quantum dots (QDs) using non-intentionally doped and p-doped QD barriers was investigated to compare their performance for use in optical modulators. The measurements indicate that the doped QD barriers lead to a better figure of merit (FoM), defined as the ratio of the change in absorption Δα for a reverse bias voltage swing to the loss at 1 V α(1 V), FoM=Δα/α (1 V). The improved performance is due to the absence of the ground-state absorption peak and an additional component to the Stark shift. Measurements indicate that p-doping the QD barriers can lead to more than a 3x increase in FoM modulator performance between temperatures of -73 °C to 100 °C when compared with the stack with NIDQD barriers.
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Nanomaterials (Basel)
January 2025
Institute of High Pressure Physics, Polish Academy of Sciences, Sokołowska 29/37, 01-142 Warsaw, Poland.
We compare the optical properties of four diode samples differing by built-in field direction and width of the InGaN quantum well in the active layer: two diodes with standard layer sequences and 2.6 and 15 nm well widths and two diodes with inverted layer ordering (due to the tunnel junction grown before the structure) also with 2.6 and 15 nm widths.
View Article and Find Full Text PDFNanophotonics
April 2024
Department of Physics and Electronics, Osaka Metropolitan University, Gakuen-cho, Naka-ku, Sakai-shi, Osaka 599-8531, Japan.
Light-emitting diodes (LEDs) are widely used as next-generation light sources because of their various advantages. However, their luminous efficiency is remarkably low at the green-emission wavelength. The luminous efficiencies of InGaN/GaN quantum wells (QWs) significantly decrease with increasing indium content in the green wavelength region, mainly owing to the quantum-confined Stark effect (QCSE).
View Article and Find Full Text PDFACS Nano
October 2024
Department of Applied Physics, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
Efficient charge separation is essential in various optoelectronic systems, yet it continues to pose substantial challenges. Building upon the recent evidence that chiral biomolecules can function as electron spin filters, this study aims to extend the application of chirality-driven charge separation from the molecular level to the mesoscale and supramolecular scale. Utilizing cellulose nanocrystals (CNCs) derived from cellulose, the most abundant biomaterial on Earth, this research leverages their self-assembly into chiral nematic structures and their dielectric properties.
View Article and Find Full Text PDFNano Lett
October 2024
Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Avenue, Ann Arbor, Michigan 48109, United States.
ACS Nano
October 2024
Centre Energie, Matériaux et Télécommunications, Institut national de la recherche scientifique (INRS-EMT), Varennes, Québec J3X 1P7, Canada.
Ultra-dense (>4,000 pixels per inch) and highly stable full-color III-nitride nanoscale pixels are crucial for near-eye display technologies like virtual and augmented-reality glasses. In this context, InGaN-based long wavelength green microscale light-emitting diodes face major bottlenecks, such as low efficiency and inadequate wavelength stability. These challenges are associated with the presence of both nonradiative surface defects and the strain induced quantum-confined Stark effect.
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