Publications associées à Défaut ponctuel

Ultrafast carrier dynamics and insights in defect mechanism of p-type colloidal ZnO QDs

Jacques-Edouard Moser, Andrea Cannizzo, Etienne Christophe Socie, Camila Bacellar Cases Da Silveira, Victoria Kabanova

In this study, we place a strong emphasis on understanding the ultrafast dynamics of carrier recombination pathways in p-type ZnO, especially in the midgap region. Synthesizing and controlling the properties of p-type ZnO remains a pivotal yet challenging ...

SPIE2024

Electrical spectroscopy of defect states and their hybridization in monolayer MoS2

Andras Kis, Oleg Yazyev, Mukesh Kumar Tripathi, Yanfei Zhao, Ahmet Avsar, Kristians Cernevics, Zhenyu Wang, Juan Francisco Gonzalez Marin, Cheol Yeon Cheon, Hyungoo Ji

Defects in solids are unavoidable and can create complex electronic states that can significantly influence the electrical and optical properties of semiconductors. With the rapid progress in the integration of 2D semiconductors in practical devices, it is ...

Nature Research2023

Interface connection of functionalized carbon nanotubes for efficient and stable perovskite solar cells

Mohammad Khaja Nazeeruddin, Jianxing Xia, Ruiyuan Hu

The ionic defects of hetero-junction interfaces always attract and trap carriers via surface electrostatic forces, which are crucial for the efficiency and intrinsic stability of perovskite solar cells (PSCs). Herein, functionalized carbon nanotubes (CNTs) ...

Royal Society of Chemistry2023

From defect to effect: controlling electronic transport in chevron graphene nanoribbons

Oleg Yazyev, Kristians Cernevics

While bottom-up synthesis allows for precise control over the properties of graphene nanoribbons (GNRs), the use of certain precursor molecules can result in edge defects, such as missing benzene rings that resemble a 'bite'. We investigate the adverse eff ...

IOP Publishing Ltd2023

The nanoscale impact of individual nonradiative point defects on InGaN/GaN quantum wells

Thomas Fjord Kjaersgaard Weatherley

Today's world depends on optoelectronic devices: light-emitting diodes illuminate our houses and backlight the displays on our gadgets, while laser diodes underpin fibre-optic communication. Such optoelectronic devices rely on crystalline semiconductor het ...

EPFL2023

GeSn as next-generation material for short-wave infrared single-photon detection

Andrea Giunto

In recent years, the automotive industry has aspired to bring self-driving vehicles to the general public and light detection and ranging (LiDAR) sensors have emerged as the preferred solution for car vision systems. At present, LiDAR technologies employ e ...

EPFL2023

Correlating light-induced deep defects and phase segregation in mixed-halide perovskites

Quentin Thomas Jeangros, Jakub Holovsky, Christian Michael Wolff, Peter Joseph Fiala, Xin Yu Chin

Mixed-halide perovskites are highly promising materials for tandem solar cells. The phenomenon of phase segregation, however hinders their application. Here, we combine Fourier-Transform photocurrent spectroscopy with photoluminescence and current density- ...

Royal Society of Chemistry2022

Deep defects in InGaN LEDs: modeling the impact on the electrical characteristics

Nicolas Grandjean, Jean-François Carlin, Camille Haller

Deep defects have a fundamental role in determining the electro-optical characteristics and in the efficiency of InGaN light-emitting diodes (LEDs). However, modeling their effect on the electrical characteristics of the LED is not straightforward. ...

SPIE-INT SOC OPTICAL ENGINEERING2022

Stoichiometry modulates the optoelectronic functionality of Zinc Phosphide (Zn3-xP2+x)

Anna Fontcuberta i Morral, Elias Zsolt Stutz, Santhanu Panikar Ramanandan, Mischa Samuel Flór, Jean-Baptiste Leran, Diego Armando Sandoval Salaiza, Mahdi Zamani, Simon Robert Escobar Steinvall, Rajrupa Paul, Mirjana Dimitrievska, Maria Chiara Spadaro

Predictive synthesis–structure–property relationships are at the core of materials design for novel applications. In this regard, correlations between the compositional stoichiometry variations and functional properties are essential for enhancing the perf ...

2022

In Operando, Photovoltaic, and Microscopic Evaluation of Recombination Centers in Halide Perovskite-Based Solar Cells

Ulf Anders Hagfeldt, Henry Snaith, Silver Hamill Turren Cruz

The origin of the low densities of electrically active defects in Pb halide perovskite (HaP), a crucial factor for their use in photovoltaics, light emission, and radiation detection, remains a matter of discussion, in part because of the difficulty in det ...

AMER CHEMICAL SOC2022

Nanoscale Growth Initiation as a Pathway to Improve the Earth-Abundant Absorber Zinc Phosphide

Anna Fontcuberta i Morral, Elias Zsolt Stutz, Jean-Baptiste Leran, Mahdi Zamani, Simon Robert Escobar Steinvall, Rajrupa Paul, Mirjana Dimitrievska

Growth approaches that limit the interface area between layers to nanoscale regions are emerging as a promising pathway to limit the interface defect formation due to mismatching lattice parameters or thermal expansion coefficient. Interfacial defect mitig ...

AMER CHEMICAL SOC2022

Modeling the electrical characteristic of InGaN/GaN blue-violet LED structure under electrical stress

Nicolas Grandjean, Jean-François Carlin, Camille Haller

The role of deep defects and their physical origin in InGaN/GaN LED are still widely investigated and debated, in particular their impact on the electrical and optical characteristics and on the reliability of the device. In this paper we evaluate the elec ...

PERGAMON-ELSEVIER SCIENCE LTD2022

Defect-induced magnetism in homoepitaxial SrTiO3

Mihai Adrian Ionescu, Daesung Park

Along with recent advancements in thin-film technologies, the engineering of complex transition metal oxide heterostructures offers the possibility of creating novel and tunable multifunctionalities. A representative complex oxide is the perovskite stronti ...

AIP Publishing2022

Wafer-scale MoS2 with water-vapor assisted showerhead MOCVD

Aleksandra Radenovic, Andras Kis, Mukesh Kumar Tripathi, Mukeshchand Thakur, Michal Daniel Macha, Yanfei Zhao, Hyungoo Ji, Jing Zhang

Among numerous thin film synthesis methods, metalorganic chemical vapor deposition performed in a showerhead reactor is the most promising one for broad use in scalable and commercially adaptable two-dimensional material synthesis processes. Adapting the m ...

ROYAL SOC CHEMISTRY2022

Disorder-induced electronic, magnetic, and optoelectronic properties of two-dimensional materials

Cheol Yeon Cheon

Technological advancement has been in cadence with material development by improving the purity of single crystals and, at the same time, controlling their imperfections. These capabilities have been especially vital for developing new technolo-gies based ...

EPFL2022

Demonstrating and Unraveling a Controlled Nanometer-Scale Expansion of the Vacancy Defects in Graphene by CO2

Kumar Varoon Agrawal, Kuang-Jung Hsu, Luis Francisco Villalobos Vazquez de la Parra

A controlled manipulation of graphene edges and vacancies is desired for molecular separation, sensing and electronics applications. Unfortunately, available etching methods always lead to vacancy nucleation making it challenging to control etching. Herein ...

Wiley-VCH Verlag GmbH2022

Effects of quantum-well indium content on deep defects and reliability of InGaN/GaN light-emitting diodes with under layer

Nicolas Grandjean, Jean-François Carlin, Camille Haller

We investigate the density of defects and the degradation rate in InGaN light-emitting diodes having identical dislocation density and epitaxial structure, but different indium content in the quantum well (QW; 12%, 16%, 20%). Our results, based on combined ...

IOP PUBLISHING LTD2021

Systematic design of millisecond gasification reactor for the incorporation of gas-sieving nanopores in single-layer graphene

Kumar Varoon Agrawal, Kuang-Jung Hsu, Luis Francisco Villalobos Vazquez de la Parra, Shiqi Huang, Shaoxian Li

Etching an ensemble of vacancy defects (nanopores) in single-layer graphene (SLG) to obtain a high density of nanopores with an effective size that enables high-performance gas sieving is challenging. This is because nanopore nucleation and expansion are u ...

2021

Interaction of Confined Polaritons in Microcavity Structures

Morteza Navadeh Toupchi

A polariton is a quasiparticle formed from the coupling of a confined photon in a cavity to electronic excitation, like exciton in a semiconductor. This dissertation reports on series of experiments in confined polariton interaction by design, fabrication, ...

EPFL2021

Millisecond lattice gasification for high-density CO2- and O2-sieving nanopores in single-layer graphene

Emad Oveisi, Kumar Varoon Agrawal, Marina Micari, Mounir Driss Mensi, Luis Francisco Villalobos Vazquez de la Parra, Mostapha Dakhchoune, Shiqi Huang, Shaoxian Li, Deepu Joseph Babu

Etching single-layer graphene to incorporate a high pore density with sub-angstrom precision in molecular differentiation is critical to realize the promising high-flux separation of similar-sized gas molecules, e.g., CO2 from N2. However, rapid etching ki ...

2021