A5071302778- Semiconductor Quantum Structures and Devices
- Advanced Semiconductor Detectors and Materials
- Semiconductor Lasers and Optical Devices
- GaN-based semiconductor devices and materials
- Spectroscopy and Laser Applications
- Photonic and Optical Devices
- Chalcogenide Semiconductor Thin Films
- Nanowire Synthesis and Applications
- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Physics of Superconductivity and Magnetism
- Superconducting and THz Device Technology
- Photonic Crystals and Applications
- Advancements in Semiconductor Devices and Circuit Design
- Fern and Epiphyte Biology
- Heusler alloys: electronic and magnetic properties
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
University of Surrey
2014-2020
Philipps University of Marburg
2014-2015
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...
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...
Using photovoltage (PV) spectroscopy we analyse the electronic structure of a series GaBixAs/(Al)GaAs dilute bismide quantum well (QW) laser structures. The use polarisation-resolved PV measurements allows us to separately identify transitions involving bound light- and heavy-hole states in QWs, as bound-to-continuum from QWs barriers. Analysis these enables probe conduction valence band offsets, thereby quantifying offsets. 12-band Hamiltonian, extract offsets explicitly by constraining...
We report pressure-dependent photoluminescence (PL) experiments under hydrostatic pressures up to 2.16 GPa on a mid-wave infrared InAs/InAs0.86Sb0.14 type-II superlattice (T2SL) structure at different pump laser excitation powers and sample temperatures. The pressure coefficient of the T2SL transition was found be 93 ± 2 meV·GPa−1. integrated PL intensity increases with 1.9 then quenches rapidly indicating induced level crossing conduction band states ∼2 GPa. Analysis as function power 0,...
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...
Critical point transition energies and optical functions of the novel GaAs-based dilute bismide alloys GaAsBi, GaNAsBi, GaPAsBi were determined using spectroscopic ellipsometry. The ellipsometry data analyzed a parameterized semiconductor model to represent dielectric function as sum Gaussian oscillators centered on critical points in band structure, from this extracting those points. gap spin-orbit splitting measured for samples range alloy compositions. first experimental measurements...
Abstract Using spectroscopic ellipsometry measurements on GaP 1− x Bi /GaP epitaxial layers up to = 3.7% we observe a giant bowing of the direct band gap ( $${E}_{g}^{{\rm{\Gamma }}}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mrow> <mml:mi>E</mml:mi> </mml:mrow> <mml:mi>g</mml:mi> <mml:mi>Γ</mml:mi> </mml:msubsup> </mml:math> ) and valence spin-orbit splitting energy (Δ SO ). is measured decrease (increase) by approximately 200 meV (240 meV) with...
Photonic crystal cavities enable the realization of high Q-factor and low mode-volume resonators, with typical architectures consisting a thin suspended periodically patterned layer to maximize confinement light by strong index guiding. We investigate heterostructure-based approach comprising refractive core lower cladding layers. While typically decreases decreasing contrast between layers, we show that, counterintuitively, due provided photonic band structure in it becomes possible achieve...
Interband cascade lasers (ICLs) are a promising light source for the mid-infrared (mid-IR) spectral range. However, certain applications such as spectroscopic techniques chemical sensing and non-invasive disease diagnostics, broadband incoherent radiation an LED may be more desirable. Here we investigate both ICLs interband emitting devices (ICLEDs). The ICLEDs follow example of by cascading multiple active stages in series to improve efficiency increase output power, but without optical...
We present a theoretical analysis of the optoelectronic properties type-II GaAs <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</sub> Bi xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> /GaN xmlns:xlink="http://www.w3.org/1999/xlink">y</sub> As xmlns:xlink="http://www.w3.org/1999/xlink">1-y</sub> quantum wells( QWs) grown on substrates. eludicate broad scope for band structure engineering in these novel heterostructures, demonstrating that...
Using spectroscopic ellipsometry measurements on GaP$_{1-x}$Bi$_{x}$/GaP epitaxial layers up to $x = 3.7$% we observe a giant bowing of the direct band gap ($E_{g}^Γ$) and valence spin-orbit splitting energy ($Δ_{\textrm{SO}}$). $E_{g}^Γ$ ($Δ_{\textrm{SO}}$) is measured decrease (increase) by approximately 200 meV (240 meV) with incorporation 1% Bi, corresponding greater than fourfold increase in $Δ_{\textrm{SO}}$ going from GaP GaP$_{0.99}$Bi$_{0.01}$. The evolution $x$ characterised...
GaAsBi QWs have the potential to remove inherent recombination losses thereby increasing efficiency and reducing temperature sensitivity of near-infrared telecommunications lasers. QW lasers are reported prospects for 1550nm operation discussed.
We demonstrate a new class of GaAs-based type II quantum wells based on the highly mis-matched III–V semiconductor alloys GaAs <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1-x</inf> Bi xmlns:xlink="http://www.w3.org/1999/xlink">x</inf> and GaNyAs xmlns:xlink="http://www.w3.org/1999/xlink">1-y</inf> . theoretically quantify analyse available design space for growth /GaN xmlns:xlink="http://www.w3.org/1999/xlink">y</inf> As structures GaAs. Our...
Highly-mismatched III-V semiconductor alloys containing dilute concentrations of bismuth (Bi) have attracted significant attention in recent years since their unique electronic properties open up a range possibilities for practical applications lasers, photovoltaics, spintronics, photodiodes, and thermoelectrics. Research on bismide has primarily focused to date <tex xmlns:mml="http://www.w3.org/1998/Math/MathML"...