A5029606462- Semiconductor Quantum Structures and Devices
- Semiconductor Lasers and Optical Devices
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- GaN-based semiconductor devices and materials
- Advanced Semiconductor Detectors and Materials
- Solid State Laser Technologies
- Laser Design and Applications
- Quantum Dots Synthesis And Properties
- Chalcogenide Semiconductor Thin Films
- Semiconductor materials and devices
- Perovskite Materials and Applications
- ZnO doping and properties
- Advanced Fiber Laser Technologies
- Ga2O3 and related materials
- Conducting polymers and applications
- Semiconductor materials and interfaces
- Nanowire Synthesis and Applications
- Thin-Film Transistor Technologies
- Silicon Nanostructures and Photoluminescence
- Electronic and Structural Properties of Oxides
- Organic Light-Emitting Diodes Research
- Plasma Diagnostics and Applications
- Acoustic Wave Resonator Technologies
- Advanced Photonic Communication Systems
University of Glasgow
2024
University of Surrey
2015-2024
Philipps University of Marburg
2022
Schott (Germany)
2017
University of California, Santa Barbara
2017
Technical University of Munich
2017
Benue State University
2017
National Academy of Sciences of Belarus
1997-2004
B.I. Stepanov Institute of Physics
2000-2002
Institute for Technical Physics and Materials Science
1980
The Ga(AsBi) material system opens opportunities in the field of high efficiency infrared laser diodes. We report on growth, structural investigations, and lasing properties dilute bismide Ga(AsBi)/(AlGa)As single quantum well lasers with 2.2% Bi grown by metal organic vapor phase epitaxy GaAs (001) substrates. Electrically injected operation at room temperature is achieved a threshold current density 1.56 kA/cm2 an emission wavelength ∼947 nm. These results from broad area devices show...
Abstract Over the last decade, 2,2″,7,7″‐Tetrakis[ N , ‐di(4‐methoxyphenyl)amino]‐9,9′‐spirobifluorene (spiro‐OMeTAD) has remained hole transporting layer (HTL) of choice for producing high efficiency perovskite solar cells (PSCs). However, PSCs incorporating spiro‐OMeTAD suffer significantly from dopant induced instability and non‐ideal band alignments. Herein, a new approach is presented tackling these issues using functionality organometallocenes to bind Li + ions, rendering them immobile...
Abstract Successful manipulation of halide perovskite surfaces is typically achieved via the interactions between modulators and perovskites. Herein, it demonstrated that a strong‐interaction surface modulator beneficial to reduce interfacial recombination losses in inverted (p‐i‐n) solar cells (IPSCs). Two organic ammonium salts are investigated, consisting 4‐hydroxyphenethylammonium iodide 2‐thiopheneethylammonium (2‐TEAI). Without thermal annealing, these two can recover photoluminescence...
Abstract Electrically pumped GaAsBi/GaAs quantum well lasers are a promising new class of near-infrared devices where, by use the unusual band structure properties GaAsBi alloys, it is possible to suppress dominant energy-consuming Auger recombination and inter-valence absorption loss mechanisms, which greatly impact upon device performance. Suppression these mechanisms promises lead highly efficient, uncooled operation telecommunications lasers, making system strong candidate for...
Interface-mediated recombination losses between perovskite and charge transport layers are one of the main reasons that limit device performance, in particular for open-circuit voltage (VOC) solar cells (PSCs). Here, functional molecular interface engineering (FMIE) is employed to retard interfacial losses. The FMIE a facile solution-processed means introducing molecules, fluorene-based conjugated polyelectrolyte (CPE) organic halide salt (OHS) on both contacts absorber layer. Through FMIE,...
The radiative and nonradiative components of the threshold current in 1.3μm, p-doped undoped quantum-dot semiconductor lasers were studied between 20 370K. complex behavior can be explained by simply assuming that recombination Auger rates are strongly modified thermal redistribution carriers dots. large differences devices arise due to trapped holes devices. These both greatly increase involving hole excitation at low temperatures decrease electron escape their Coulombic attraction. model...
We investigate the temperature and pressure dependence of light-current characteristics electroluminescence spectra GaAs1−xBix/GaAs light emitting diodes. The emission wavelength shows a relatively low coefficient peak shift 0.19 ± 0.01 nm/K. A strong decrease in efficiency with increasing implies that non-radiative recombination plays an important role on performance these devices. GaAs0.986Bi0.014 bandgap is measured to be 11.8 0.3 meV/kbar. intensity from GaAsBi found accompanied by...
This paper reports on progress in the development of GaAsBi/(Al)GaAs based lasers grown using metal-organic vapour phase epitaxy and focuses underlying processes governing their efficiency temperature dependence. Room lasing has been achieved devices with 2.2% Bi 4.4% was observed up to 180 K. We show that device performance can be improved by optimizing both electrical optical confinement laser structures. Analysis dependence threshold current together pure spontaneous emission high...
Replacing small amounts of As with Bi in InGaBiAs/InP induces large decreases and increases the bandgap, Eg, spin-orbit splitting, ΔSO, respectively. The possibility achieving ΔSO > Eg a reduced temperature (T) dependence for are significant suppressing recombination losses improving performance mid-infrared photonic devices. We measure Eg(x, T) (x, In0.53Ga0.47BixAs1−x/InP samples 0 ≤ x 0.039 by various complementary optical spectroscopic techniques. While we find no clear evidence...
Bismuth-containing III-V alloys open-up a range of possibilities for practical applications in semiconductor lasers, photovoltaics, spintronics, photodiodes, and thermoelectrics. Of particular promise the development lasers is possibility to grow GaAsBi laser structures such that spin-orbit splitting energy (ΔSO) greater than bandgap (E <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) active region devices operating around telecom...
Abstract In this work we study the nature of band gap in GeSn alloys for use silicon-based lasers. Special attention is paid to Sn-induced mixing effects. We demonstrate from both experiment and ab-initio theory that (direct) Γ-character changes continuously with alloy composition has significant even at low (6%) Sn concentrations. The evolution due conduction effects, contrast sharp indirect-to-direct transition obtained conventional such as Al 1−x Ga x As. Understanding effects critical...
Abstract We report on the key design factors for development of Type-II “W”-lasers O-band (1260-1360 nm) applications. investigated effects InGaAs and GaAsSb Quantum Well (QW) composition thicknesses emission wavelength recombination efficiency as well (Al,Ga)As barriers optimum electrical optical confinement. Photoluminescence tests structures full device were fabricated characterised. 1.25 µm emitting lasers demonstrated with threshold current density, Jth values 480±10 A/cm2 at 290 K,...
We report modulation of the absorption coefficient at 1.3 μm in Ge/SiGe multiple quantum well heterostructures on silicon via quantum-confined Stark effect. Strain engineering was exploited to increase direct optical bandgap Ge wells. grew 9 nm-thick wells a relaxed Si0.22Ge0.78 buffer and contrast factor greater than 3.2 achieved spectral range 1290–1315 nm.
A combined growth approach involving both molecular-beam epitaxy and metal-organic vapor phase has been developed to fabricate GaAsBi/GaAs-based quantum well (QW) laser structures with a Bi composition up 8%. Lasing operation demonstrated at room temperature 1.06 μm in diodes containing 3QWs that turn contain approximately 6% Bi. 5QW device lasing 1.09 80 K. Using temperature- pressure-dependent measurements of stimulated emission as pure spontaneous measurements, we show the threshold...
InAs quantum-dot (QD) lasers were investigated in the temperature range 20-300 K and under hydrostatic pressure of 0-12 kbar at room temperature. The results indicate that Auger recombination is very important 1.3-μm QD it is, therefore, possible cause relatively low characteristic observed, T/sub 0/=41K. In 980-nm where 0/=110-130 K, radiative dominates. laser emission photon energy E/sub las/ increases linearly with p 10.1 8.3 meV/kbar for 980 nm lasers, respectively. For threshold current...
The efficiency limiting mechanisms in type-I GaInAsSb-based quantum well (QW) lasers, emitting at 2.3 µm, 2.6 µm and 2.9 are investigated.Temperature characterization techniques measurements under hydrostatic pressure identify an Auger process as the dominant non-radiative recombination mechanism these devices.The results supplemented with from three additional GaInAsSb extending wavelength range investigation 1.85-2.90μm.Under pressure, contributions CHCC CHSH to threshold current density...
Abstract The potential to extend the emission wavelength of photonic devices further into near- and mid-infrared via pseudomorphic growth on conventional GaAs substrates is appealing for a number communications sensing applications. We present new class GaAs-based quantum well (QW) heterostructure that exploits unusual impact Bi N band structure produce type-II QWs having long wavelengths with little or no net strain relative GaAs, while also providing control over important laser loss...
We show that even in quantum-dot (QD) lasers with very low threshold current densities (J th = 40-50 A/cm 2 at 300 K), the temperature sensitivity of arises from nonradiative recombination comprises ∼60% to 70% J K, whereas radiative part is almost insensitive.The influence mechanism decreases increasing hydrostatic pressure and band gap, which leads a decrease current.We also studied, for first time, gap dependence , contrast increases strongly gap.These results suggest Auger an important...
Abstract To investigate carrier scattering processes in short wavelength InAs/AlSb quantum cascade lasers we carried out experimental and theoretical studies of the threshold current, I th , as a function high hydrostatic pressure temperature. Using calculated dependence optical phonon ph estimated leakage leak show that from upper laser levels into indirect L‐valley conduction band InAs wells is negligible 3.3 μm QCLs at RT leading to their superior temperature performance. In shorter...
The temperature dependence of the radiative and nonradiative components threshold current density 1.3 mum InAs/GaAs quantum-dot lasers have been analyzed both experimentally theoretically. It is shown that weak variation measured for arises because optical matrix element excited state transitions significantly smaller than ground transition. In contrast, Auger recombination can a similar probability involving states as those carriers. sharp increase in at high temperatures follows cubed...
The impact of carrier density non‐pinning above threshold on laser performance is studied in different quantum dot/dash lasers with room temperature emission wavelengths 0.98–1.52 µm. Owing to inhomogeneity the active region, may be important even because non‐thermal distribution between dots. This has a large external differential efficiency and output power devices. In presence non‐radiative recombination, will further decrease slope significant reduction number carriers available for...
The threshold current and its radiative component in 1.5μm InAs∕InP (311)B quantum dot lasers are measured as a function of the temperature. Despite an almost temperature insensitive current, increases steeply with leading to characteristic T0≈55K around 290K. Direct observation spontaneous emission from wetting layer shows that some leakage dots occurs these devices. However, decrease pressure is also suggesting Auger recombination dominates nonradiative sensitivity