A5000759941- Terahertz technology and applications
- Semiconductor Quantum Structures and Devices
- Perovskite Materials and Applications
- Superconducting and THz Device Technology
- Photonic and Optical Devices
- Advanced Memory and Neural Computing
- Conducting polymers and applications
- Semiconductor Lasers and Optical Devices
- Silicon Nanostructures and Photoluminescence
- Transition Metal Oxide Nanomaterials
- Millimeter-Wave Propagation and Modeling
- Organic Electronics and Photovoltaics
- Semiconductor materials and devices
- Photoreceptor and optogenetics research
- Photonic Crystals and Applications
- Molecular Junctions and Nanostructures
- Fullerene Chemistry and Applications
- stochastic dynamics and bifurcation
- Solid-state spectroscopy and crystallography
- Microwave Engineering and Waveguides
- Quantum and electron transport phenomena
- Nanomaterials and Printing Technologies
- GaN-based semiconductor devices and materials
- Chalcogenide Semiconductor Thin Films
- solar cell performance optimization
Universitat Jaume I
2020-2024
University of the Philippines Diliman
2015-2021
University of the Philippines System
2018
An investigation of the kinetic behavior MAPbI3 memristors shows that onset voltage to a high conducting state depends strongly on sweep rate, and impedance spectra generate complex capacitive inductive patterns. We develop dynamic model describe these features obtain physical insight into coupling ionic electronic properties produce resistive switching behavior. The separates memristive response distinct diffusion transition-state-formation steps well experimental current–voltage curves at...
Perovskite solar cells show a number of internal electronic-ionic effects that produce hysteresis in the current-voltage curves and dependence temporal response on conditions previous stimulus applied to sample. There are many models explanations literature, but predictive methods may lead an assessment cell behavior based independent measurements needed. Here, we develop method predict time domain starting from frequency measured by impedance spectroscopy over collection steady states. The...
Metal halide perovskite (MHP) devices often show different types of hysteresis in separate voltage domains. At low voltage, the impedance response is capacitive, and cell gives regular hysteresis. high inverted, corresponding to an inductive that causes a negative capacitance feature. We calculate current due chemical inductor model, we inversely proportional scan rate. formulate general dynamical model for solar style neuronal models action potential, based on few differential equations....
Abstract Halide perovskites are promising candidates for resistive memories (memristors) due to their mixed electronic/ionic conductivity and the real activation mechanism is currently under debate. In order unveil role of metal contact its connection with process, four model systems screened on halide perovskite memristors: Nearly inert metals (Au Pt), low reactivity contacts (Cu), highly reactive (Ag Al), pre‐oxidized in form AgI. It revealed that threshold voltage memory effect connected...
With the increasing demand for artificially intelligent hardware systems brain-inspired in-memory and neuromorphic computing, understanding underlying mechanisms in resistive switching of memristor devices is paramount importance. Here, we demonstrate a two-step set process involving complex interplay among mobile halide ions/vacancies (I–/VI+) silver ions (Ag+) perovskite-based memristors with thin undoped buffer layers. The involves an initial gradual increase current associated...
Solution-processed photodetectors such as those based on halide perovskite semiconductors show attractive properties for emerging applications in lightweight, transparent, flexible, and spectrally selective optical sensors. The transient photocurrent to a light perturbation often shows complex response characterized by sharp peaks the curves when stimulus changes or slow rise times depending features applied voltage active layer thickness. We present characteristic of measuring...
With the increasing demands and complexity of neuromorphic computing schemes utilizing highly efficient analog resistive switching devices, understanding apparent capacitive inductive effects in device operation is paramount importance. Here, we present a systematic array characterization methods that unravel two distinct voltage-dependent regimes demonstrating complex interplay between dynamic volatile perovskite-based memristors: (1) low voltage capacitance-dominant (2) an...
The evolution of device properties in memristor switching between high- and low-resistance states is critical for applications still highly subjected to significant ambiguity. Here, we present the dynamic state transition a 2D Ruddlesden–Popper perovskite-based device, measured via impedance spectroscopy. spectral exhibits transformation low frequency arc negative capacitance arc, further decreasing resistance. capacitance–frequency indicates that appearance intimately related slow kinetic...
Memristors stand out as promising components in the landscape of memory and computing. are generally defined by a conductance mechanism containing state variable that imparts effect. The current–voltage cycling causes transitions conductance, which determined different physical mechanisms, such formation conducting filaments an insulating surrounding. Here, we provide unified description set reset processes using conductance-activated quasi-linear memristor (CALM) model with unique...
Halide perovskite is very attractive for the fabrication of energy‐efficient memristors neuromorphic applications. However, reproducibility, stability, and understanding switching behavior still lag in comparison to other technologies. Herein, a deep‐level obtained by development highly reproducible devices. The approach based on stable formulation (MAPbBr 3 ) use preoxidized silver (AgI) as buffer layer. Here, reliable with device yields approaching 100%, stabilities >10 4 cycles...
Inkjet printing (IJP) of polymer solar cells is ideal for small‐area off‐grid electronics with low power consumption. However, IJP quite a complex technique compared techniques such as spin coating or doctor blading. The blends reported based on ITIC derivatives non‐fullerene acceptors (NFAs) using non‐halogenated solvents. results show that fluorination NFA essential to form highly stable inks in o‐xylene, because has significantly insufficient solubility ITIC‐4F. importance tetralin...
Lead halide perovskites suffer from uncontrolled ion migration and the interactions at external contacts play a fundamental role in hysteretic response performance degradation kinetics. In this work, we passivate interfaces by reaction of migrating iodide ions with silver buffer layer placed between Spiro-OMeTAD Au layers. presence an electrical field, iodine occurs that are close to perovskite/contact interface irreversibly form AgI. Overall, interfacial totally suppresses hysteresis leads...
The carrier lifetimes and electron mobility values were estimated for 2 μm thick GaAs films grown on Si (100) substrates by means of optical pump terahertz probe (OPTP) technique. GaAs/Si measured epitaxial at different substrate temperatures (TS = 520 °C or TS 630 °C). From x-ray diffraction measurements Raman spectroscopy, the shown to experience minimum strain room temperature, crystal misorientation in (111) (110) direction. With no measureable photoluminescence via OPTP found be ∼20 ∼35...
Carrier dynamics and photoconductivity in epitaxial-grown low-temperature GaAs on nominal vicinal Si(1 0 0) substrates ('LT-GaAs/Si') were studied to predict their actual performance as THz photoconductive antenna (PCA) detectors. An optical-pump terahertz-probe technique was used obtain the transmittance, carrier lifetime of two LT-GaAs/Si samples, grown using different growth protocols. The LT-GaAs substrate with a 4° tilt 〈1 1 0〉 has better crystallinity, agreement other reports; while...
Two asymmetric double quantum wells of different coupling strengths (barrier widths) were grown via molecular beam epitaxy, both samples allowing tunneling. Photoluminescence was measured at 10 and 300 K to provide evidence tunneling, barrier dependence, structural uniformity. Carrier dynamics room temperature investigated by optical pump terahertz probe (OPTP) spectroscopy. population decay rates obtained photoconductivity spectra analyzed using the Drude model. This work demonstrates that...
Abstract We present the implementation of an efficient terahertz (THz) photoconductive antenna (PCA) emitter design that utilizes high mobility carriers in two-dimensional electron gas (2DEG) a modulation-doped heterostructure (MDH). The PCA is fabricated with recessed metal electrodes direct contact 2DEG region MDH. compare performance MDH having contacts on bulk semi-insulating GaAs, low temperature-grown and surface. By recessing contacts, applied bias can effectively accelerate...
Memristors stand out as promising components in the landscape of memory and computing. are generally defined by a conductance equation containing state variable that imparts effect. The current-voltage cycling causes transitions conductance, determined different physical mechanisms such formation conducting filaments an insulating surrounding. Here we provide unified description set reset processes, means single voltage activated relaxation time variable. This approach is based on...
GaAs films were grown on Si (100) substrates with a "two-step buffer" growth technique using molecular beam epitaxy, wherein low temperature buffer is at two substrate temperatures prior to the layer. Results of layer different are compared photoluminescence, Raman, and optical-pump terahertz-probe spectroscopy.
Epitaxial low temperature grown GaAs (LT-GaAs) on silicon (LT-GaAs/Si) has the potential for terahertz (THz) photoconductive antenna applications. However, crystalline, optical and electrical properties of heteroepitaxial LT-GaAs/Si can be very different from those semi-insulating substrates (reference). In this study, we investigate an epitaxial sample, compared to a reference under same substrate temperature, with layer thickness. Anti-phase domains some crystal misorientation are present...
Bowtie photoconductive antennas (PCAs) with a 10-μm gap were fabricated on epitaxial grown LT-GaAs layers Silicon substrates (LT-GaAs-on-Si). The samples used distinct growth parameters. performance of the PCAs as terahertz detectors are presented in this report.
We investigate strain effects on the ultrafast carrier dynamics and transport of gallium arsenide films silicon (GaAs/Si) magnesium oxide (GaAs/MgO) substrates using temperature-dependent photoluminescence (PL) terahertz time-domain spectroscopy (THz-TDS) from 11 K - 300 K. The PL shows that GaAs/Si GaAs/MgO samples are under tensile compressive at low temperature, respectively. THz emission does not show significant differences with bulk GaAs, while an order-of-magnitude decrease...