Photo-electrical properties of 2D quantum confined metal–organic chalcogenide nanocrystal films

Nanoscale ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 233-241
Author(s):  
Lorenzo Maserati ◽  
Mirko Prato ◽  
Stefano Pecorario ◽  
Bianca Passarella ◽  
Andrea Perinot ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electrical Properties ◽  
Quantum Wells ◽  
Charge Carriers ◽  
Metal Contacts ◽  
Chalcogenide Material ◽  
Metal Organic ◽  
Nanocrystal Films ◽  
Quantum Confined ◽  
Photo Detection

[AgSePh]∞ is a metal–organic chalcogenide material featuring hybrid quantum wells electronic structure. Photo-generated charge carriers can be extracted by metal contacts, enabling efficient UV photo-detection.

Quantum-confined stark effect and localization of charge carriers in Al0.3Ga0.7N/Al0.4Ga0.6N quantum wells with different morphologies

2012 ◽  
Vol 46 (8) ◽  
pp. 998-1002 ◽  
Author(s):  
E. A. Shevchenko ◽  
V. N. Jmerik ◽  
A. M. Mizerov ◽  
A. A. Sitnikova ◽  
S. V. Ivanov ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Charge Carriers ◽  
Quantum Confined Stark Effect ◽  
Quantum Confined ◽  
Localization Of Charge Carriers

Intersubband Transitions in GaN/AlxGa1-xN Multi Quantum Wells

2004 ◽  
Vol 829 ◽  
Author(s):  
E. A. DeCuir ◽  
Y. C. Chua ◽  
B. S. Passmore ◽  
J. Liang ◽  
M. O. Manasreh ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Chemical Vapor ◽  
Charge Carriers ◽  
Organic Chemical ◽  
Multiple Quantum ◽  
Intersubband Transitions ◽  
Metal Organic ◽  
Si Doped ◽  
Organic Chemical Vapor Deposition ◽  
Absorption Technique

ABSTRACTIntersubband transitions (ISTs) in GaN/AlxGa1-xN multiple quantum wells (MQWs) were investigated using an optical absorption technique. Several samples were grown by either Molecular Beam Epitaxy (MBE) or Metal-Organic Chemical Vapor Deposition (MOCVD) and were investigated using both normal incident and waveguide configurations. The waveguides were fabricated by dicing each sample into 2 mm wide by 5 mm long pieces with two facets polished at 45 degrees with respect to the surface such that light propagates across the sample's width. Preliminary results indicate that ISTs are observable in Si-doped and undoped GaN/AlxGa1-xN MQWs. The source of these charge carriers in the undoped samples are explained as being due to the spontaneous polarization effect which exists at the GaN/AlxGa1-xN interfaces where the GaN surface has Ga-polarity. Scanning Electron Microscopy indicates that a sample containing what appeared to be a large number of cracks and or hexagonal voids lacked the presence of ISTs.

Photoluminescence and Recombination Mechanisms in Nitride-Based Multiple Quantum Wells

2015 ◽  
Vol 764-765 ◽  
pp. 1250-1254
Author(s):  
Ya Fen Wu ◽  
Jiunn Chyi Lee
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Multiple Quantum Well ◽  
Chemical Vapor ◽  
Organic Chemical ◽  
Multiple Quantum ◽  
Incident Power ◽  
Quantum Confined Stark Effect ◽  
Metal Organic ◽  
Quantum Confined

The InGaN/AlGaN multiple-quantum-well heterostructures were fabricated by metal-organic chemical vapor deposition system with different indium and aluminum content during the growth of InGaN well layers and AlGaN barrier layers. Temperature-and incident-power-dependent photoluminescence were carried out to examine the recombination mechanisms in the heterostructures. Both of the localization effect and quantum-confined Stark effect are considered. From the experimental and theoretical analysis, the dependence of optical characteristics on the temperature and incident-power are consistent with the recombination mechanisms involving band-tail states and the screen of quantum-confined Stark effect.

The quantum-confined Stark effect and localization of charge carriers in AlxGa1-xN/AlyGa1-yN quantum wells with different morphologies

2013 ◽  
Vol 10 (3) ◽  
pp. 319-322
Author(s):  
E. A. Shevchenko ◽  
V. N. Jmerik ◽  
A. M. Mizerov ◽  
D. V. Nechaev ◽  
A. A. Sitnikova ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Stark Effect ◽  
Charge Carriers ◽  
Quantum Confined Stark Effect ◽  
Quantum Confined ◽  
Localization Of Charge Carriers

The morphologies and electrical properties of indium contacts on (100) cadmium telluride surfaces

1992 ◽  
Vol 50 (2) ◽  
pp. 1422-1423
Author(s):  
A.M. Letsoalo ◽  
M.E. Lee ◽  
E.O. de Neijs
Keyword(s):  
Electrical Properties ◽  
Cadmium Telluride ◽  
Methanol Solution ◽  
Electrical Characteristics ◽  
Metal Contacts ◽  
Deposition Technique ◽  
Interfacial Layers ◽  
Semiconductor Contacts ◽  
Grown Single Crystal ◽  
Diamond Abrasive

Semiconductor devices require metal contacts for efficient collection of electrical charge. The physics of these metal/semiconductor contacts assumes perfect, abrupt and continuous interfaces between the layers. However, in practice these layers are neither continuous nor abrupt due to poor nucleation conditions and the formation of interfacial layers. The effects of layer thickness, deposition rate and substrate stoichiometry have been previously reported. In this work we will compare the effects of a single deposition technique and multiple depositions on the morphology of indium layers grown on (100) CdTe substrates. The electrical characteristics and specific resistivities of the indium contacts were measured, and their relationships with indium layer morphologies were established.Semi-insulating (100) CdTe samples were cut from Bridgman grown single crystal ingots. The surface of the as-cut slices were mechanically polished using 5μm, 3μm, 1μm and 0,25μm diamond abrasive respectively. This was followed by two minutes immersion in a 5% bromine-methanol solution.

The quantum confined Pockels effect in GaAs-based multi-quantum wells

1999 ◽  
Vol 09 (PR2) ◽  
pp. Pr2-37 ◽  
Author(s):  
O. Krebs ◽  
P. Voisin ◽  
D. Rondi ◽  
J. L. Gentner ◽  
L. Goldstein ◽  
...  
Keyword(s):  
Quantum Wells ◽  
Pockels Effect ◽  
Quantum Confined

Relation Between Local Structure, Electric Dipole and Charge Carrier Dynamics in DHICA Melanin, a Model for Biocompatible Semiconductors

2019 ◽  
Author(s):  
Micaela Matta ◽  
Alessandro Pezzella ◽  
Alessandro Troisi
Keyword(s):  
Electronic Structure ◽  
Degrees Of Freedom ◽  
Structural Model ◽  
Computational Study ◽  
Oxidative Polymerization ◽  
Radical Scavenging ◽  
Charge Carriers ◽  
Electronic Charge ◽  
Polymer Semiconductors ◽  
Synthetic Pigments

<div><div><div><p>Eumelanins are a family of natural and synthetic pigments obtained by oxidative polymerization of their natural precursors: 5,6 dihydroxyindole and its 2-carboxy derivative (DHICA). The simultaneous presence of ionic and electronic charge carriers makes these pigments promising materials for applications in bioelectronics. In this computational study we build a structural model of DHICA melanin considering the interplay between its many degrees of freedom, then we examine the electronic structure of representative oligomers. We find that a non-vanishing dipole along the polymer chain sets this system apart from conventional polymer semiconductors, determining its electronic structure, reactivity toward oxidation and localization of the charge carriers. Our work sheds light on previously unnoticed features of DHICA melanin that not only fit well with its radical scavenging and photoprotective properties, but open new perspectives towards understanding and tuning charge transport in this class of materials.<br></p></div></div></div>

Message Passing Neural Networks for Partial Charge Assignment to Metal-Organic Frameworks

2020 ◽  
Author(s):  
Ali Raza ◽  
Arni Sturluson ◽  
Cory Simon ◽  
Xiaoli Fern
Keyword(s):  
Electronic Structure ◽  
Message Passing ◽  
Gas Adsorption ◽  
Metal Organic Frameworks ◽  
Computational Cost ◽  
Electronic Structure Calculations ◽  
High Fidelity ◽  
Partial Charges ◽  
Metal Organic ◽  
Structure Calculations

Virtual screenings can accelerate and reduce the cost of discovering metal-organic frameworks (MOFs) for their applications in gas storage, separation, and sensing. In molecular simulations of gas adsorption/diffusion in MOFs, the adsorbate-MOF electrostatic interaction is typically modeled by placing partial point charges on the atoms of the MOF. For the virtual screening of large libraries of MOFs, it is critical to develop computationally inexpensive methods to assign atomic partial charges to MOFs that accurately reproduce the electrostatic potential in their pores. Herein, we design and train a message passing neural network (MPNN) to predict the atomic partial charges on MOFs under a charge neutral constraint. A set of ca. 2,250 MOFs labeled with high-fidelity partial charges, derived from periodic electronic structure calculations, serves as training examples. In an end-to-end manner, from charge-labeled crystal graphs representing MOFs, our MPNN machine-learns features of the local bonding environments of the atoms and learns to predict partial atomic charges from these features. Our trained MPNN assigns high-fidelity partial point charges to MOFs with orders of magnitude lower computational cost than electronic structure calculations. To enhance the accuracy of virtual screenings of large libraries of MOFs for their adsorption-based applications, we make our trained MPNN model and MPNN-charge-assigned computation-ready, experimental MOF structures publicly available.<br>

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