We report a study of transport blockade features in a quantum dot single-electron transistor, based on an undoped AlGaAs/GaAs heterostructure. We observe suppression of transport through the ground state of the dot, as well as negative differential conductance at finite source-drain bias. The temperature and magnetic field dependences of these features indicate the couplings between the leads and the quantum dot states are suppressed. We attribute this to two possible mechanisms: spin effects which determine whether a particular charge transition is allowed based on the change in total spin, and the interference effects which arise from coherent tunnelling of electrons in the quantum dot.
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http://dx.doi.org/10.1088/0953-8984/25/50/505302 | DOI Listing |
Nanoscale
January 2025
Department of Chemistry, Maulana Azad National Institute of Technology, Bhopal-462003, India.
Mixing different metal ions at the B site of ABX perovskites offers a promising approach for addressing challenges related to toxicity, stability and performance in optoelectronic applications. One such example is CsPbSnBr which addresses the toxicity issue posed by lead while allowing us to tune optoelectronic properties such as the band gap. In this work, nearly monodisperse CsPbSnBr quantum dots (QDs) were synthesized with variable Pb/Sn compositions, CsPbBr, CsPbSnBr and CsPbSnBr.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
LPHE-MS, Faculty of Science, Mohammed V University in Rabat, Morocco.
This study explores the optoelectronic and photovoltaic potential of acceptor-π-donor (A-π-D) architectures utilizing CSi quantum dots (CSiQDs) through a combination of density functional theory (DFT) and time-dependent DFT (TDDFT). We examined two key structural configurations: C-C and Si-C conformers. In these systems, CSiQDs serve as the acceptor, CHSF as the π-bridge, and 3 × (CHO) as the donor.
View Article and Find Full Text PDFHeliyon
January 2025
Department of Physics, Facility of Science, King Abdulaziz University, Jeddah, Saudi Arabia.
The influence of variations in indium concentration and temperature on threshold current density (J) in In Ga As/GaAs ( = 0, 0.8 and 0.16) quantum dot (QD) laser diodes - synthesized via molecular beam epitaxy (MBE) with three distinct indium concentrations on GaAs (001) substrates - was meticulously examined.
View Article and Find Full Text PDFHeliyon
January 2025
Department of Chemistry and Biochemistry, Thapar Institute of Engineering and Technology, Patiala, 147004, India.
Deep eutectic solvents (DESs) have attracted significant attention in recent years due to its environment friendly characteristics and its participation in the multi-heteroatom doping of carbon quantum dots (CQDs). In this work, we present a simple, fast, and environment-friendly microwave synthesis approach for the synthesis of DES-assisted nitrogen and chloride co-doped CQDs (N,Cl-CQDs) using a choline chloride-urea based DES. A biomass-based precursor, i.
View Article and Find Full Text PDFJ Phys Chem C Nanomater Interfaces
January 2025
Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, U.K.
Using many-body perturbation theory, we study the optical properties of phenylthiolate-capped cadmium sulfide nanoparticles to understand the origin of the experimentally observed blue shift in those properties with decreasing particle size. We show that the absorption spectra predicted by many-body perturbation theory agree well with the experimentally measured spectra. The results of our calculations demonstrate that all low-energy excited states correspond to a mixture of two fundamental types of excitations: intraligand and ligand-to-metal charge-transfer excitations.
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