A5012399255- Semiconductor Quantum Structures and Devices
- GaN-based semiconductor devices and materials
- Semiconductor materials and devices
- ZnO doping and properties
- Semiconductor Lasers and Optical Devices
- Spectroscopy and Laser Applications
- Advanced Semiconductor Detectors and Materials
- Plasmonic and Surface Plasmon Research
- Superconducting and THz Device Technology
- Quantum Dots Synthesis And Properties
- Radio Frequency Integrated Circuit Design
- Thermal Radiation and Cooling Technologies
- Metamaterials and Metasurfaces Applications
- Gas Sensing Nanomaterials and Sensors
- Advancements in Semiconductor Devices and Circuit Design
- Photonic and Optical Devices
- Chalcogenide Semiconductor Thin Films
- Acoustic Wave Resonator Technologies
- Optical Coatings and Gratings
- Photonic Crystals and Applications
- Atmospheric Ozone and Climate
- Nanowire Synthesis and Applications
- Conducting polymers and applications
- Terahertz technology and applications
- Copper-based nanomaterials and applications
Universidad Politécnica de Madrid
2011-2023
Institut für Sozialforschung und Sozialwirtschaft
2018
Institute of Photonic Sciences
2015-2017
Universidad Complutense de Madrid
2017
University of Bristol
2011-2015
Bristol Robotics Laboratory
2013-2014
Tribunal Electoral del Estado de México
2010
HRL Laboratories (United States)
2000-2005
Universidad Autónoma de Madrid
2004-2005
Abstract Large area flexible electronics rely on organic or hybrid materials prone to degradation limiting the device lifetime. For many years, photo‐oxidation has been thought be one of major pathways. However, intense illumination may lead a burn‐in rapid decrease in performance for devices completely isolated from corrosive elements as oxygen moisture. The experimental studies which are presented here indicate that plausible triggering is spin flip after UV photon absorption leading...
The degradation of AlGaN/GaN high electron mobility transistors after off-state stress is studied by means electroluminescence (EL) analysis, gate leakage current (Ig) monitoring, and atomic force microscopy (AFM) mapping the semiconductor surface. It found that Ig upon due to combined effect individual defects underlying each EL spots, which contribute a few μA total Ig. After removal contacts passivation, direct one-to-one correspondence between spots pits on surface found. Reverse bias,...
The length of the transit region a Gunn diode determines natural frequency at which it operates in fundamental mode—the shorter device, higher operation. long-held view on design is that for functioning device minimum about 1.5 μm, limiting devices to mode operation frequencies roughly 60 GHz. Study these by more advanced Monte Carlo techniques simulate ballistic transport and electron-phonon interactions govern behaviour, offers new lower bound 0.5 already being approached experimental...
Micro-Raman thermography, microphotoluminescence spectroscopy, and thermal simulation were used to study the properties of AlGaN/GaN heterostructure field-effect transistors grown on semi-insulating bulk GaN substrates. A conductivity 260 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{W}\cdot\hbox{m}^{-1} \cdot\hbox{K}^{-1}$</tex></formula> was determined from temperature measurements...
We present the first results of a planar Gunn diode made in In <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.53</sub> Ga xmlns:xlink="http://www.w3.org/1999/xlink">0.47</sub> As on an InP substrate, operating at fundamental frequency up to 164 GHz. For 120-μm-wide device with 1.3- μm active channel length, highest power achieved was approximately -10 dBm
We have developed a method to grow and characterize the state of art non-polar ZnO/(Zn,Mg)O multi-quantum wells on m-plane ZnO substrates as prerequisite for applications based intersubband transitions. The epilayer interfaces exhibit low roughness, layer thickness remains constant within one monolayer in these heterostructures. optical properties been studied UV IR domains by means photoluminescence absorption experiments, respectively. In UV, is very well described an excitonic transition,...
Herein we report a thin and robust interconnecting layer for polymer tandem solar cells where high fill factor is achieved.
This paper reports on the demonstration of quantum cascade detectors (QCDs) based ZnO/ZnMgO wells (QWs) grown by molecular beam epitaxy an m-plane ZnO substrate. The TM-polarized intersubband absorption is peaked at a 3 μm wavelength. sample has been processed in form square mesas with sizes ranging from 10 × μm2 up to 100 μm2. I-V characteristics reveal that 86% 260 devices are operational and surface leakage current negligible room temperature, which not case 77 K. photocurrent...
Transparent conducting oxides (TCOs) are widely used in applications from solar cells to light emitting diodes. Here, we show that the metal organic chemical vapor deposition (MOCVD)-grown, rock-salt CdZnO ternary, has excellent potential as a TCO. To assess this compound, use combination of infrared reflectance and ultraviolet-visible absorption spectroscopies, together with Hall effect, determine its optical electrical transport characteristics. It is found incorporation Zn produces an...
The ZnO-based heterostructures are predicted to be promising candidates for optoelectronic devices in the infrared and terahertz (THz) spectral domains owing their intrinsic material properties. Specifically, large ZnO LO-phonon energy reduces thermally activated scattering, which is greatly improve temperature performance of THz quantum cascade lasers. However, date, no experimental observation intersubband emission from has been reported. Here, we report electroluminescence ZnO/MgxZn1–xO...
Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation N. Killat, M. Montes Bajo, T. Paskova, K. R. Evans, J. Leach, X. Li, Ü. Özgür, H. Morkoç, D. Chabak, A. Crespo, Gillespie, Fitch, Kossler, E. Walker, Trejo, G. Via, Blevins, Kuball; Reliability of AlGaN/GaN high electron mobility transistors on low dislocation density bulk GaN substrate: Implications surface...
The evolution of AlGaN/GaN high electron mobility transistors under off-state stress conditions is studied by gate leakage current (Ig) monitoring, electroluminescence (EL), and atomic force microscope (AFM) imaging at room temperature. It found that the number failure sites as identified EL increases over time during until it reaches a saturation value. Ig accordingly this reached. AFM scanning device surface stripped metal contacts passivation reveals pits corresponding to location spots....
Unexpected light propagation effects, such as negative refraction, have been reported in artificial media. Leveraging on the intersubband resonances heterostructured semiconductors, we show that all possible optical regimes, ranging from classical dieletric and metal to hyperbolic metamaterial types 1 2, can be achieved. As a demonstration, prove refraction effect occur at designed frequency by controlling electronic quantum confinement.
Highly doped multiple quantum wells (MQWs) are significant for infrared optoelectronics, plasmonics, and the physics of strong light-matter coupling. The authors reveal a multisubband plasmon (MSP) that arises from couplings among several intersubband transitions in (Mg,Zn)O/ZnO MQWs, due to outstandingly dense two-dimensional electron gas. Here MSP energy is up three times constituent transitions, illustrating potential this system optoelectronic applications infrared, which could be...
The possibility of an independent tuning the electron and hole confinement in InAs/GaAs quantum dots (QDs) by using a thin GaAsSbN capping layer (CL) is studied. By controlling Sb N contents quaternary alloy, band structure QDs can be broadly tuned converted from type-II valence (high contents) to type-I conduction contents). Nevertheless, simultaneous presence found induce strain composition inhomogeneities CL degrade photoluminescence structure.
Solution-processed ZnO sol–gel or nanoparticles are widely used as the electron-transporting layer (ETL) in optoelectronic devices. However, chemisorbed oxygen on surface has been shown to be detrimental for device performance well stability. Herein, we demonstrate that removal based UV illumination of under a nitrogen atmosphere can, simultaneously, improve power conversion efficiency and photostability PTB7-Th:PC71BM-based inverted polymer solar cells. By systematic study such procedure,...
The temperature dependence of the emission spectrum Cr3+ ions in Sr0.6Ba0.4 (NbO3)2 has been systematically investigated around ferroelectric phase transition this crystal (≈370 K). In spite strong thermal quenching luminescence occurring at these temperatures, is still clearly detectable and shows dramatic changes both line shape intensity when passing through temperature. A redshift about 6 nm occurs driven from polar to nonpolar phase. addition, shift displays a hysteresis, then providing...
A series of light-emitting diodes (LEDs) with active layers based on InAs quantum dots (QDs) covered by GaAsSb capping is presented. Varying the Sb content in layer from <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex Notation="TeX">${\sim}{2}$</tex></formula> to xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\sim}28\%$</tex></formula> , room temperature electroluminescence (EL) 1.15 1.5...
Impact ionization in GaAs-based planar Gunn diodes is studied through electroluminescence (EL) analysis with the aim of reducing its magnitude by means contact design and shaping, thus enhance device performance reliability. Designs which diode ohmic anode has an overhanging Schottky extension (composite contact) are shown to result a significantly reduced amount impact ionization, as compared simple design. The EL results consistent Monte Carlo simulations, show composite devices due...
We report a 72.8 GHz fully static frequency divider in AlInAs/InGaAs HBT IC technology. The CML operates with 350 mV logic swing at less than 0 dBm input power up to maximum clock rate of 63 and requires 86 the minimum GHz. Power dissipation per flip-flop is 55 mW 3.1 V supply. To our knowledge this highest operation for any power-delay product 94 fJ/gate also lowest circuit operating above 50 A low on same substrate 36 6.9 dissipated delay 24 is, knowledge, 30
Laser action at 1.06μm from a neodymium aluminium borate microchip laser crystal has been demonstrated under F3∕24 direct excitation 882nm. We have found that the slope efficiency increases 50% up to 70% when resonant pumping is used instead of traditional I9∕24→F5∕24(808nm) pumping. conclude reduction in pump-induced heat generation achieved by origin this improvement.
We report on continuous-wave and subnanosecond passively Q-switched laser oscillation from a NdAl3BO34 microchip operating at 1.06 µm. Efficient stable operation is possible only when resonant pumping (I49/2?F43/2 882 nm) used instead of the traditional I49/2?F45/2 (808 pumping. The improvement in performance caused by strong reduction pump-induced thermal loading, which achieved directly into emitting level.
Gate leakage degradation of AlGaN/GaN high electron mobility transistors under OFF-state stress is investigated using a combination electrical, optical, and surface morphology characterizations. The generation “hot spots” at the edge gate found to be strongly temperature accelerated. time for formation each failure site follows Weibull distribution with shape parameter in range 0.7–0.9 from room up 120 °C. average per only weakly dependent. stress-induced structural sites exhibits dependence...
The development of new nanophotonic devices requires the understanding and modulation propagating surface plasmon phonon modes arising in plasmonic polar dielectric materials, respectively. Here we explore CdZnO alloy as a material, with tunable plasma frequency reduced losses compared to pure CdO. By means attenuated total reflectance, experimentally observe hybridization polariton (SPP) (SPhP) air-CdZnO-sapphire three-layer system. We show how through precise control thickness, resonance...