arXiv subjects

Mourad Benamara

Publications and source records attributed to Mourad Benamara.

8 recordsLinked to original sources

arXiv2026

Investigation of GeSn aspect ratio trapping growth up to 8% Sn

Aspect ratio trapping (ART) growth of germanium-tin (GeSn) is a promising approach to target important objectives on the quest towards commercialization of complementary metal-oxide-semiconductor (CMOS)-compatible GeSn optoelectronics devices. Its local growth on patterned substrate allows for versatile device integration into photonics integrated circuit or for stand-alone structure like focal plane array imager. Additionally, high aspect ratio from nano-sized window can terminate early threading dislocation propagation on the oxide sidewalls, leaving subsequent growth defect-free and potentially improving the device performance. Knowledge remains missing regarding GeSn ART growth kinetics, morphology and how they evolve from thin film growth, with successful growth itself yet to be demonstrated. In this work, we report GeSn ART growth up to 8% Sn. Two configurations -- self-induced Ge core/GeSn shell for Sn content between 6% and 8%, and bulk GeSn ART for Sn content below 1% -- are observed. We present a comprehensive study on GeSn ART growth kinetics through different growth rounds and designs, showing a link between pyramid shape of ART island and successful Sn incorporation, as well as the role of growth selectivity and local heating.

cond-mat.mtrl-sci↗

arXiv2026

Systematic study of high performance GeSn photodiodes with thick absorber for SWIR and extended SWIR detection

Germanium-tin (GeSn) photodiodes potentiate a viable solution to integrate SWIR and extended SWIR detection technology into CMOS processing line. However, challenges in the growth of thick, high quality GeSn limit the device absorber thickness, making it impossible to ascertain the performance limit of GeSn photodiodes. An in-depth understanding of their device physics and a clear optimization pathway towards commercial-grade devices remain elusive. This work presents a systematic empirical study of GeSn photodiodes with thick absorber (2 to 8% Sn content, up to 2630 nm thick), showing high responsivity up to 0.59 A.W-1 at 1.55 {\mu}m and 0.43 A.W-1 at 2 {\mu}m wavelengths, low dark current density down to 2 x 10-2 A.cm-2, and high detection cutoff wavelengths up to 2.1 and 2.5 {\mu}m at 5% and 8% Sn, respectively. Using specific doping design (P-i-N and N-i-P), an in-depth analysis is presented on the impact of junction position, p-type background carrier concentration, bulk/ surface defects and photocarrier diffusion length - on photodetection performance. Different optimization strategies for GeSn photodiodes, in particular at high Sn content, are proposed.

physics.ins-det↗

arXiv2026

Interface-Driven Growth Mode Control of 2D GaSe on 3D GaAs Substrates with Distinct Crystallographic Orientations

Previous studies of the growth of two-dimensional (2D) gallium selenide (GaSe) by molecular beam epitaxy (MBE) on a gallium arsenide (GaAs) three-dimensional (3D) substrate have reported significant differences in growth morphology, polytype, and the nature of the interface. The results differ, ranging from GaSe 2D film growth at tilted 2D planes to observed spiral structures, thereby calling for a deeper understanding of the impact of the substrate interface on the growth of GaSe films. In this paper, we conduct a comprehensive reexamination of the growth mechanism of GaSe on GaAs substrates with (211)B and (001)B orientations, investigating the nature of the 2D/3D interface and the resulting morphology of the 2D GaSe films. We do this by investigating different methods of preparation of the GaAs substrate surface before the growth of GaSe by MBE, the importance of which has not been considered before. Our results resolve the mechanistic origin of tilted versus non-tilted 2D growth and establish a general interface-driven orientation selection rule linking substrate symmetry and dangling-bond coordination to layered heteroepitaxy. This framework provides a scalable interface-engineering pathway for deterministic control of layered chalcogenide heterostructures and enables wafer-scale integration with established semiconductor device platforms.

cond-mat.mtrl-sci↗

arXiv2026

Chemical Vapor Deposition Growth and Characterization of ReSe2

Two-dimensional (2D) flakes of ReSe2 structure were grown by chemical vapor deposition and investigated at room temperature using Raman, photoluminescence, and absorption spectroscopies. The Raman spectra revealed eighteen phonon modes in the range of 100-300 cm-1 that were found in good agreement with the density functional theory (DFT) calculations. The thickness profiles of the ReSe2 flakes are in the range of 5-50 nm. The ReSe2 crystal structure and morphology were investigated using XRD, atomic force microscopy and scanning electron microscopy. The energy dispersion spectroscopy confirmed the 1:2 elemental composition. The absorption spectra were obtained for ReSe2 flakes and found to exhibit excitonic peaks in the spectral region of 885 - 942 nm. These peaks are used to define the band gap of the material. The DFT calculations predicted an indirect bandgap of 0.88 eV for the bulk structure, while a direct bandgap of 1.26 eV was predicted for the monolayer.

cond-mat.mtrl-sci↗

arXiv2025

Phase Coherent Transport in Two-Dimensional Tellurium Flakes

Elemental tellurium (Te) is a compelling van der Waals material due to its interesting chiral crystal structure and predicted topological properties. Here, we report the fabrication and comprehensive quantum transport study of devices based on Te flakes with varying thicknesses. We demonstrate a hole mobility reaching up to 1000 cm2/V.s in a 17 nm thick flake at 30 Kelvin. At deep cryogenic temperatures (< 50mK), the transport characteristics transition from Coulomb blockade in the low carrier density regime to pronounced Fabry-P\'erot (F-P) interference at higher densities. Notably, the visibility of these F-P oscillations is significantly enhanced in the thinner flake device. The application of a magnetic field reveals a clear Zeeman splitting of the conductance peaks. The rich variety of quantum transport phenomena observed underscores the high quality of our thin Te flakes and establishes them as a promising platform for exploring novel physics and device concepts, such as topological superconductivity and low-power spintronic applications.

cond-mat.mes-hall↗

arXiv2025

Direct Bandgap Photoluminescence of GeSn grown on Si(100) substrate by Molecular Beam Epitaxy Growth

Group IV alloys of GeSn have gained significant attention for electronic and optoelectronic applications on a Si platform due to their compatibility with existing CMOS technology, tunable band structure, and potential for a direct bandgap at high Sn concentrations. However, synthesizing Sn-rich GeSn structures remains challenging due to the low solid solubility of Sn in Ge (less than 1%) and the substantial lattice mismatch ( about 14%) between Sn and Ge. In this work, we demonstrate the successful growth of high-quality, relaxed GeSn layers with Sn contents of 9.2% and 11.4% on Si(100) substrates via molecular beam epitaxy (MBE). As far as we know, this is the first report of direct bandgap photoluminescence observed from MBE-grown GeSn films without post-growth annealing. Structural characterizations including X-ray diffraction (XRD), secondary ion mass spectrometry (SIMS), and transmission electron microscopy (TEM) confirm uniform Sn incorporation with minimal defect formation. Atomic force microscopy (AFM) reveals smooth surfaces with low roughness. Temperature-dependent photoluminescence (PL) measurements further confirm direct bandgap emission, representing a new stage in the development of MBE-grown GeSn.

physics.app-ph↗

arXiv2024

Electrically Injected mid-infrared GeSn laser on Si operating at 140 K

Owing to its true direct bandgap and tunable bandgap energies,GeSn alloys are increasingly attractive as gain media for mid-IR lasers that can be monolithically integrated on Si. Demonstrations of optically pumped GeSn laser at room under pulsed condition and at cryogenic temperature under continuous-wave excitation show great promise of GeSn lasers to be efficient electrically injected light sources on Si. Here we report electrically injected GeSn lasers using Fabry-Perot cavity with 20, 40, and 80 micron ridge widths. A maximum operating temperature of 140 K with lasing threshold of 0.756 kA/cm2 at 77 K and emitting wavelength of 2722 nm at 140 K was obtained. The lower threshold current density compared to previous works was achieved by reducing optical loss and improving the optical confinement. The peak power was measured as 2.2 mW/facet at 77 K.

physics.optics↗

arXiv2013

Molecular Beam Epitaxial Growth of Bi2Te3 and Sb2Te3 Topological Insulators on GaAs (111) Substrates: A Potential Route to Fabricate Topological Insulator p-n Junction

High quality Bi2Te3 and Sb2Te3 topological insulators films were epitaxially grown on GaAs (111) substrate using solid source molecular beam epitaxy. Their growth and behavior on both vicinal and non-vicinal GaAs (111) substrates were investigated by reflection high-energy electron diffraction, atomic force microscopy, x-ray diffraction, and high resolution transmission electron microscopy. It is found that non-vicinal GaAs (111) substrate is better than a vicinal substrate to provide high quality Bi2Te3 and Sb2Te3 films. Hall and magnetoresistance measurements indicate that p type Sb2Te3 and n type Bi2Te3 topological insulator films can be directly grown on a GaAs (111) substrate, which may pave a way to fabricate topological insulator p-n junction on the same substrate, compatible with the fabrication process of present semiconductor optoelectronic devices.

cond-mat.mtrl-sci↗