Bouraoui Ilahi

Université de Sherbrooke | UdeS · Interdisciplinary Institute for Technological Innovation

Single crystal germanium (Ge) membranes have recently gained increasing interest for lightweight and low-cost solar cells and flexible optoelectronic devices. These membranes achieved similar material quality as bulk Ge substrate. However, the control of the membrane detachment is still challenging. In this work, we explore post-growth engineering...

Germanium (Ge) substrates are employed for III-V multijunction solar cells (MJSCs). However, due to limited availability and environmental impact, Ge is a critical raw material. Detachable Ge nanomembranes (NMs) are gaining attention to reduce Ge consumption through substrate reuse. The Porous germanium Efficient Epitaxial LayEr Release (PEELER) pr...

Germanium (Ge) is a critical material for applications in space solar cells, integrated photonics, infrared imaging, sensing, and photodetectors. However, the corresponding cost and limited availability hinder its potential for widespread applications. However, using Ge freestanding membranes (FSMs) allows for a significant reduction in the materia...

New massive markets for space multijunction solar cells are being discussed globally. For such an explosive increase in demand to materialize, a more sustainable and affordable Ge substrate technology is required. To this end, lithography-based Ge-on-Nothing and electrochemical process-based porous Ge wafers were developed. Both approaches yield un...

Porous Germanium (PGe) has emerged as a promising material for applications such as substrate engineering, sensing, and energy storage, thanks to its uniquely versatile and tunable properties. The bipolar electrochemical etching (BEE) method is widely regarded as the go-to approach for producing high-quality PGe layers. However, the lack of profoun...

III‐V solar cells are mainly grown on GaAs or Ge substrate, which significantly contributes to the final cost and affects the sustainable use of these rare materials. We developed a so‐called PEELER process in which a porosification technique is used to create a weak layer between a Ge substrate and the epitaxial layers. This method enables the sep...

Reducing both the cost and weight of Germanium (Ge)-based devices is a key concern in extending these technologies to mainstream applications. In this framework, the porous Ge lift-off, based on a mesoporous Ge layer (PGe), shaped by bipolar electrochemical etching (BEE), constitutes an appealing strategy allowing the separation of lightweight, fle...

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronics, photovoltaics, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, wei...

Semiconductor-based freestanding membranes (FSM) have recently emerged as a highly promising area of advanced materials research. Their unique properties, such as lightweight and flexibility, make them attractive for a wide range of disruptive device applications. However, the production of high-quality, single-crystalline FSM, especially from elem...

Porous germanium (PGe) nanostructures attract a lot of attention for various emerging applications due to their unique properties. Consequently, there is an increasing need for the development of low-cost synthesis routes that are compatible with large-scale production. Bipolar electrochemical etching (BEE) is a widely used solution for producing p...

The utilization of amorphous germanium-tin (Ge1-xSnx) semiconducting thin films as temperature-sensing layers in microbolometers was recently presented and patented. The work in this paper was performed as an extension of the latest study to acquire better Sn concentrations % for microbolometer applications. In this work, Ge1-xSnx thin films with v...

A perfectly compliant substrate would allow the monolithic integration of high-quality semiconductor materials such as Ge and III-V on Silicon (Si) substrate, enabling novel functionalities on the well-established low-cost Si technology platform. Here, we demonstrate a compliant Si substrate allowing defect-free epitaxial growth of lattice mismatch...

The utilization of amorphous germanium-tin (Ge 1 − x Sn x ) semiconducting thin films as temperature sensing layers in microbolometers was recently presented and patented. The work in this paper started by extending the latest study to acquire better characteristics of the Sn concentrations % for microbolometer applications. In this work, Ge1-xSnx...

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weigh...

A perfectly compliant substrate would allow the monolithic integration of high-quality semiconductor materials such as Ge and III-V on Silicon (Si) substrate, enabling novel functionalities on the well-established low-cost Si technology platform. Here, we demonstrate a compliant Si substrate allowing defect-free epitaxial growth of lattice mismatch...

In this paper, the prospect of using amorphous Si1-xSnx alloys as alternative temperature sensing active materials in microbolometers is evaluated by studying their temperature-dependent resistive properties as well as their infrared optical properties. Si1-xSnx thin films (200 nm thick), with varying Sn concentrations, are prepared at room tempera...

We investigate the ultrafast photoconductivity and charge-carrier transport in thermally annealed Fe-implanted InGaAs/InP films using time-resolved terahertz spectroscopy. The samples were fabricated from crystalline InGaAs films amorphized with Fe ions implantation. The rapid thermal annealing of the InGaAs layer induces solid recrystallization thro...

We have investigated the impact of thermal annealing gaseous atmosphere of argon, nitrogen, and forming gas on the structural and optical properties of thin polycrystalline AlN films subjected to high-energy zirconium ions implantation. X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and atomic force microscopy measurements sho...

The epitaxy of III-V semiconductors on silicon substrates remains challenging because of lattice parameter and material polarity differences. In this work, we report on the Metal Organic Chemical Vapor Deposition (MOCVD) and characterization of InAs/GaAs Quantum Dots (QDs) epitaxially grown on quasi-nominal 300 mm Ge/Si(001) and GaAs(001) substrate...

The emergence of semiconductor nanowires (NWs) as a new class of functional materials has generated a great interest in the scientific community in the fields of electronics, photonics and energy. In this work, we report on the optical properties of telecom-band emitting InAs/InP quantum rod-nanowires (QR-NWs) grown on silicon substrates by gold ca...

We investigate charge transport and photocarrier dynamics in graphene-mesoporous silicon nanocomposites using optical-pump terahertz-probe measurements. The nanocomposite material consists of a free-standing mesoporous silicon membrane whose specific surface is coated with a few-layer graphene shell. Temporal decays of the differential transmission...

Capping InAs/GaAs quantum dots (QDs) with a thin GaAsSb layer alters the QDs structural properties, leading to considerable changes in their optical properties. The increase of the Sb content induces a redshift of the emission energies, indicating a change in the buried QDs shape and size. The presence of well-defined ground- and excited-state emis...

The impact of vertical electrical field on the electron related linear and 3rd order nonlinear optical properties are evaluated numerically for pyramidal GeSn quantum dots with different sizes. The electric field induced electron confining potential profile’s modification is found to alter the transition energies and the transition dipole moment, p...

In this paper, we study the resistance versus temperature characteristics of Ge1-xSnx thin film alloys to assess the possibility of using them for temperature sensing layers in microbolometers. Ge1-xSnx thin films, with 200 nm thicknesses, are deposited at room temperature using simultaneous RF and DC sputter deposition from Ge and Sn targets. Acco...

The effects of self-organized GeSn/Ge quantum dot's size and shape on the direct band gap interband emission energy, oscillator strength and radiative lifetime are evaluated. The electron's and the hole's confined energies and their corresponding wave function are driven by solving the 3D Schrodinger equation in Cartesian coordinates using the fini...

Intersubband optical transitions, refractive index changes, and absorption coefficients are numerically driven for direct bandgap strained GeSn/Ge quantum dots. The linear, third-order nonlinear and total, absorption coefficients and refractive index changes are evaluated over useful dot sizes’ range ensuring p-like Γ-electron energy state to be lo...

Strain-engineered self-assembled GeSn/GeSiSn quantum dots in Ge matrix have been numerically investigated aiming to study their potentiality towards direct bandgap emission in the mid-IR range. The use of GeSiSn alloy as surrounding media for GeSn quantum dots (QD) allows adjusting the strain around the QD through the variation of Si and/or Sn comp...

Porous Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ferroelectric ceramics were fabricated using a solid-state reaction consisting of BCZT and poly(methyl methacrylate)(PMMA) (2%, 4%, 8% and 10% by wt.%) as a pore former. By increasing the PMMA content from 0% to 10%, porosity increased from 8% to 29%. It was found that the dielectric constant (εr ) decreased a...

The effects of post-growth thermal annealing of InAs QD with the high in-content strain reducing layer (SRL) on the temperature dependent PL properties have been investigated. The as-grown QD have shown an atypical behavior manifested by a sigmoidal emission energy and V-shaped linewidth evolution with temperature. These behaviors have been progres...

This work investigates the antibacterial potential of TiO2 based glass‐ceramic. A glass of TiO2 microcrystals embedded in glass matrix of BaO‐TiO2‐B2O3was obtained by melt quench method followed by controlled heat treatment at the 650°C for 3 hours. Crystallization of anatase phase of TiO2 was confirmed by X‐ray diffraction. UV‐visible absorbance a...

This work reports on the investigation of the thermal induced carriers’ transfer mechanism in vertically stacked bimodal size distribution InAs/GaAs quantum dots (QD). A model treating the QD as a localized states ensemble (LSE) has been employed to fit the atypical temperature dependence of the photoluminescence (PL) emission energies and linewidt...

The effects of the wetting layer thickness (t WL) on the electronic properties of direct band gap type-I strained dome shaped Ge(1−x)Snx quantum dot (QD) embedded in Ge matrix is numerically studied. The emission wavelength and the energy difference between S and P electron levels have been evaluated as a function of t WL for different QD size and...

A synthesis method has been developed for preparation of vanadium oxide thermometer thin film for microbolometer application. The structure presented is a 95-nm thin film prepared by sputter-depositing nine alternating multilayer thin films of vanadium pentoxide (V2O5) with thickness of 15 nm and vanadium with thickness of 5 nm followed by postdepo...

This work reports on a theoretical study of the optimal size and composition of Ge1−xSnx quantum dots (QD) on buffered Ge on a Si substrate for direct band gap type I light emitters. The heavy holes and electron confined energy in Γ and L points are evaluated for strained ellipsoidal QD with different sizes and composition. An applicability criteri...

Vanadium oxide (VxOy) multilayer sandwich structures previously studied by our group were found to yield a sensitive thermometerthin filmmaterial suitable for microbolometer applications. In this work, we aim to estimate the performance of a proposed air-bridge microbolometer configuration based on VxOymultilayer sandwich structurethermometerthin f...

The present study reports on the optical properties of epitaxially grown InAs quantum dots (QDs) inserted within an InGaAs strain-reducing layer (SRL). The critical energy states in such QD structures have been identified by combining photoluminescence (PL) and photoluminescence of excitation (PLE) measurements. Carrier lifetime is investigated by...

Vanadium oxide present an attractive and promising material in view of their use for bolometer detector. In fact, VO x displays unexpected properties according to the compositions. In order to improve the physical properties to be suitable for our desire application. Thermal annealing (TA) could be an effective way to limit the degradation of the c...

In this paper, we report on microstructural, optical and electrical properties of alternating multilayer of vanadium pentoxide (V2O5), 25 nm, and vanadium (V), 5 nm, thin films deposited at room temperature by radio frequency (RF) and DC magnetron sputtering, respectively. Raman and photoluminescence (PL) spectroscopy have been employed to investig...

We report on Chemical Beam Epitaxy (CBE) growth of wavelength tunable InAs/GaAs quantum dots (QD) based superluminescent diode's active layer suitable for Optical Coherence Tomography (OCT). The In-flush technique has been employed to fabricate QD with controllable heights, from 5 nm down to 2 nm, allowing a tunable emission band over 160 nm. The e...

A low cost, CMOS-compatible, and easily implementable method is presented for the synthesis of a thin film thermometer material for microbolometer applications. The thin film thermometer material was prepared by sputter depositing 11 alternative layers of vanadium pentoxide and vanadium followed by post-deposition annealing of the deposited structu...

This work reports on a chemical beam epitaxy growth study of InGaAs/GaAsInGaAs/GaAs quantum dots (QDs) engineered using an in-situ indium-flush technique. The emission energy of these structures has been selectively tuned over 225 meV by varying the dot height from 7 to 2 nm. A blueshift of the photoluminescence (PL) emission peak and a decrease of...

The effect of dot-height truncation on the device performance of multilayer InAs/GaAs quantum dot solar cells is investigated. The different structures were grown by chemical beam epitaxy, and an indium-flush process is used to control the dot height. A series of ten-layer samples with dots truncated at a height of 5 and 2.5 nm, respectively, are s...

A highly efficient third generation catalyst, CaCu 3 Ti 4 O 12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transit...

In this work, we have theoretically investigated the intermixing effect in highly strained In$_{0.3}$Ga$_{0.7}$As/GaAs quantum well (QW) taking into consideration the composition profile change resulting from in-situ indium surface segregation. To study the impact of the segregation effects on the postgrowth intermixing, one dimensional steady stat...

Devising ultrafast light-absorbing materials that are photoconductive yet resistive, have high field breakdown limits, and which can operate near 1550 nm is challenging. Their emergent needs are foreseen for photoconductive terahertz antennas, picosecond detectors, and optoelectronic switches with regard to innovative applications in data transmiss...

Devising ultrafast light-absorbing materials that are photoconductive yet resistive, have high field breakdown limits, and which can operate near 1550 nm is challenging. Their emergent needs are foreseen for photoconductive terahertz antennas, picosecond detectors, and optoelectronic switches with regard to innovative applications in data transmiss...

This paper reports on experimental and theoretical investigation of atyical temperature-dependent photoluminescence properties of InAs quantum dots in close proximity to InGaAs strain-relief underlying quantum well. The impact of a post-growth intermixing process on these properties has been studied. For the as-grown sample, the maximum of the emis...

This paper investigates the impact of the deposition rate on the mean buried InAs/GaAs quantum dots’ (QDs) size by means of a coupled photoluminescence spectroscopy and numerical approach. The proposed method consists in tuning the theoretical transition energies by changing the QDs aspect ratio towards best fit of the photoluminescence emission en...

This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Lead-free 0.715Bi0.5Na0.5TiO3-0.065BaTiO3-0.22SrTiO3 (BNT-BT-ST) bulk ferroelectric ceramic was selected for the course of investigation. 3BaO - 3TiO2 - B2O3 (BTBO) glass was then incorporated syst...

This work reports on theoretical and experimental investigation of the impact of InAs quantum dots (QDs) position with respect to InGaAs strain reducing layer (SRL). The investigated samples are grown by molecular beam epitaxy and characterized by photoluminescence spectroscopy (PL). The QDs optical transition energies have been calculated by solvi...

This paper reports on an initial assessment of the direct growth of In(Ga)As/GaAs quantum dots (QDs) solar cells on nanostructured surface Si substrate by molecular beam epitaxy (MBE). The effect of inserting 40 InAs/InGaAs/GaAs QDs layers in the intrinsic region of the heterojunction pin-GaAs/n+-Si was evaluated using photocurrent spectroscopy in...

In this work, we have theoretically investigated the intermixing effect in highly strained In0.3Ga0.7As/GaAs quantum well (QW) taking into consideration the composition profile change resulting from in-situ indium surface segregation. To study the impact of the segregation effects on the postgrowth intermixing, one dimensional steady state Schrodin...

Through the recrystallization of an amorphous heterostructure, obtained by MeV Fe ion implantation, we are able to tailor a standard epitaxial semiconductor material, a small gap InGaAsP/InP alloy, for photoconductive terahertz optoelectronics. Here, we report on microstructural changes occurring in the material over a broad range of rapid thermal...

This paper reports on the evolution of InAs/GaAs quantum dots’ (QDs) intermixing process depending on the QD position with respect to the InGaAs strain reducing layer. The postgrowth intermixing has been ensured by rapid thermal annealing (RTA) at different temperatures and the processed samples were investigated by photoluminescence (PL) spectrosc...

Optical characterization of wavelength tunable InAs QDs with (In)GaAs surrounding material O. Nasr (1), M. H. Hadj Alouane (1)*, N. Chauvin (2), H. Maaref (1), F. Hassen (1), C. Bru-Chevallier (2), L. Sfaxi (1) and B. Ilahi (1,3) (1) Université de Monastir, Laboratoire de Micro-Optoélectronique et Nanostructures, Faculté des Sciences, Avenue de l'e...

Upcoming multijunction solar cells designs intended for high concentration use will require the addition of more junctions to further increase the efficiency and/or reduce costs. Proposed designs include junctions with a bandgap around 1.70 eV [1]. Such a bandgap can be achieved with either AlGaAs or GaInAsP materials. Since the well-known sensitiv...

In this study, we investigate the effect of incorporation of Si nanowires (SiNWs) on the organic/inorganic hybrid nanocomposites based on poly [2-methoxy-5-(2'-ethylhexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and SiNWs. A huge potential for SiNWs for an amelioration of optical properties of investigated structures was shown, and particularly a more...

In this paper, we report on the impact of InAs quantum dots' (QDs) position within InGaAs strain reducing layer on their structural and optical properties. Morphological investigation revealed that the QD' size and density are strongly dependent on the InGaAs underlying layer's thickness. Additionally, comprehensive spectroscopic study by room temp...

This paper treats the impact of post growth tuned InAs/InP quantum dashes' (QDas) size/composition distribution on carriers' localization and thermal redistribution. The spread of this distribution depends on the experimental conditions used for the phosphorus ion implantation enhanced intermixing process. Atypical temperature-dependent luminescenc...

In this work, low-temperature photoluminescence (PL) and photoluminescence excitation (PLE) experiments have been carried out to investigate the optical and electronic properties of InAs/GaAs quantum dots (QDs) subjected to room-temperature proton implantation at various doses (5 × 1010–1014 ions cm−2) and subsequent thermal annealing. The energy s...

Optical properties of wurtzite InP/InAs/InP core–shell nanowires grown on silicon substrates by solid source molecular beam epitaxy are studied by means of photoluminescence and microphotoluminescence. The growth conditions were optimized to obtain purely wurtzite radial quantum wells emitting in the telecom bands with a radiative lifetime in the 5...

This paper reports on an in-situ growth process used to optimize InAs/GaAs quantum dot (QD) multilayer structures grown on (001) GaAs substrate by chemical beam epitaxy (CBE). Defects related to the incoherently relaxed InAs clusters are found to alter the QD nucleation mechanism on the subsequent layers, leading to reduced QD density and photolumi...

Structural Fingerprints in Temperature-dependent Hall Measurements after Ion Implantation Amorphization and Recrystallization of InGaAsP/InP André Fekecs (1), Bouraoui Ilahi (1), Martin Chicoine (2), François Schiettekatte (2,3), Denis Morris (1,3), and Richard Arès(1,3) 1. Institut Interdisciplinaire d'Innovation Technologique (3IT), Université...

In this paper, we report on an effective post-growth processing technique for developing semi-insulating (SI) photonic thin films absorbing in 1.3 µm. For that purpose, we examined a 1 µm thick unintentionally n-doped In0.72Ga0.28As0.61P0.39 epilayer (0.95 eV bandgap) modified by multiple-energy MeV Fe ion implantation. Fe was chosen as a deep-leve...

The effect of functionalisation of Multi-Walled CNTs (MWCNTs) as a way to ameliorate their dispersion has been quantified. Two kinds of nanocomposites have been elaborated, using a spin-coating as deposition technique: poly (2-methoxy-5-(2-ethyhexyl-oxy)-p-phenylenevinylene) (MEH-PPV) as an electron donor, pristine MWCNTs and polystyrene-functional...