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244 results on '"Maaref, Hassen"'

41. Systematic optical study of high-x InxGa1-xAs/InP structures for infrared photodetector applications

Author

Smiri Badreddine, R.S. Joshya, Demir Ilkay, Saidi Faouzi, Altuntas Ismail, Delphine Lagarde, Cedric Rober, Marie Xavier, Maaref Hassen, Eğitim Bilimleri Enstitüsü, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Université de Monastir - University of Monastir (UM), and Cumhuriyet University [Sivas, Turkey]

Subjects
FKOs, [PHYS]Physics [physics], High-xIn(x)Ga(1-x)As, PHOTOREFLECTANCE, EXCITONS, RECOMBINATION, S-shaped, Atomic and Molecular Physics, and Optics, Electronic, Optical and Magnetic Materials, SWIR detector, MODEL, LSE, TEMPERATURE-DEPENDENCE, LUMINESCENCE, Dislocation density, PHOTOLUMINESCENCE, Electrical and Electronic Engineering, Localized state
Abstract

Optical and structural properties in high-x InxGa1-xAs (x > 0.65) samples with varying indium concentration grown on InP (1 00) substrate are reported. By increasing the indium fraction, it was found by the high-resolution X-ray diffraction (HR-XRD) study that the dislocation density in the InxGa1-xAs epitaxial layer significantly increased, and the surface quality deteriorated remarkably. Photoreflectance (PR) spectra show the presence of Franz-Keldysh Oscillations (FKOs) features above the InxGa1-xAs energy bandgap. The strain-induced electric field is then estimated directly from the FKOs periods. Temperature-dependent photoluminescence (TDPL) measurements from 10 K to 300 K showed carrier locations (S-shape). This abnormal behavior is due to the dislocation density associated with fluctuations in the indium concentration. A quasi-stationary rate equation model for the temperature-dependent luminescence spectra of the localized state material system is proposed to interpret the band gap emission process quantitatively. Low-temperature (10 K) time-resolved PL measurements show the increase of lifetime with increasing the indium concentration. Yet, the addition of only 1.7% of indium concentration results in a strong enhancement of PL lifetime by ~ 80%.& nbsp;All these results reveal a more precise picture of the localization and recombination mechanisms of photo-generated carriers in the InGaAs layer, which could be the crucial factors in controlling the performance of high indium content InGaAs SWIR detector.

Published
2022

48. Double Gaussian Distribution of Inhomogeneous Barrier Height in (Ni-Au)/Al0.25Ga0.75N/GaN.

Author

Saadaoui, Salah, Fathallah, Olfa, and Maaref, Hassen

Abstract

The forward current–voltage (Ig-Vg) properties of the (Ni-Au)/Al0.25Ga0.75N/GaN/SiC structure were examined in the temperature range of 50–320K. Temperature has considerable influence on the zero-bias barrier height (ΦB0), series resistance (Rs),and ideality factor (n).Furthermore, the standard Richardson plots of ln(I0/T2) vs. 103/T for this sample revealed two linear zones (50–230 K and 230–320 K). For Al0.25Ga0.75N, the Richardson constant (A*) values in the linear zones were less than the predicted value (34.2 Acm−2K−2).This phenomenon is linked to the Schottky barrier inhomogeneities by adopting a double Gaussian distribution (GD) of the barrier heights (BHs) at the (Ni-Au)/Al0.25Ga0.75N interface. We attempted to establish an indication of the double GD of BHs for this sample by plotting ΦB0 vs. q/2kT. As a result, the Ig-Vg temperature dependency was satisfactorily described using the thermionic emission hypothesis with a double GD of the BHs at the (Ni-Au)/Al0.25Ga0.75N interface. These findings indicate that the inhomogeneous distribution of the surface and/or interface states is linked to the lateral inhomogeneity of the Schottky BH which is attributed to the defect existence confirming prior findings using the capacitance deep-level transient spectroscopy method. [ABSTRACT FROM AUTHOR]

Published
2023
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