Lakhdar Dehimi

Bio: Lakhdar Dehimi is an academic researcher from University of Batna. The author has contributed to research in topics: Diode & Schottky barrier. The author has an hindex of 15, co-authored 75 publications receiving 582 citations. Previous affiliations of Lakhdar Dehimi include University of Biskra.

Analysis of Trapping Effects on the Forward Current–Voltage Characteristics of Al-Implanted 4H-SiC p-i-n Diodes

Abstract: The forward current–voltage characteristics (IF–VF) of aluminum (Al)-implanted 4H-SiC p-i-n diodes are investigated by means of a numerical simulation study that takes into account both intrinsic and doping-induced deep defects, namely, the Z1/2 and EH6/7 centers inside the drift region and an electrically active trap concentration inside the anode region due to the Al+ ion implantation process. From the experimental results, the fundamental electric parameters of several samples were extracted at different regions of diode operation and used for comparison. The modeling analysis reveals that Z1/2 and EH6/7 centers reduce the effective carrier lifetimes and increase the recombination rate in the drift region determining the slope of the IF curve in the recombination and diffusion regimes. In addition, a defect density that becomes comparable to the epilayer doping concentration introduces an apparent shunt resistance effect at low-medium biases and at the same time has a noticeable impact on the diode series resistance at voltages higher than 2.7 V. A detrimental effect on the series resistance is also observed in dependence of the trap concentration in the anode region that increases the diode’s internal resistance as a consequence of the carrier mobility decrease. Above the IF curve knee, the diode current is largely dominated by the electron injection into the anode since the concentration of free holes for conduction is strongly limited in turn by the incomplete activation of the ion-implanted impurities and the trap activity.

Performance Analysis of a Pt/n-GaN Schottky Barrier UV Detector

Abstract: The electrical and optical characteristics of an n-type gallium nitride (GaN)-based Schottky barrier ultraviolet (UV) detector, where a platinum (Pt) metal layer forms the anode contact, have been evaluated by means of detailed numerical simulations considering a wide range of incident light intensities. By modeling the GaN physical properties, the detector current density–voltage characteristics and spectral responsivity for different (forward and reverse) bias voltages and temperatures are presented, assuming incident optical power ranging from 0.001 W cm−2 to 1 W cm−2. The effect of defect states in the GaN substrate is also investigated. The results show that, at room temperature and under reverse bias voltage of −300 V, the dark current density is in the limit of 2.18 × 10−19 A cm−2. On illumination by a 0.36-μm UV uniform beam with intensity of 1 W cm−2, the photocurrent significantly increased to 2.33 A cm−2 and the detector spectral responsivity reached a maximum value of 0.2 A W−1 at zero bias voltage. Deep acceptor trap states and high temperature strongly affected the spectral responsivity curve in the considered 0.2 μm to 0.4 μm UV spectral range.

Numerical simulations of the electrical transport characteristics of a Pt/n-GaN Schottky diode

Abstract: In this paper, using a numerical simulator, we investigated the current–voltage characteristics of a Pt/n-GaN thin Schottky diode on the basis of the thermionic emission (TE) theory in the 300 to 500 K temperature range. During the simulations, the effect of different defect states within the n-GaN bulk with different densities and spatial locations is considered. The results show that the diode ideality factor and the threshold voltage decrease with increasing temperature, while at the same time, the zero-bias Schottky barrier height (Φb0) extracted from the forward current density–voltage (J–V) characteristics increases. The observed behaviors of the ideality factor and zero-bias barrier height are analyzed on the basis of spatial barrier height inhomogeneities at the Pt/GaN interface by assuming a Gaussian distribution (GD). The plot of apparent barrier height (Φb,App) as a function of q/2kT gives a straight line, where the mean zero-bias barrier height () and the standard deviation (σ0) are 1.48 eV and 0.047 V, respectively. The plot of the modified activation energy against q/kT gives an almost the same value of and an effective Richardson constant A* of 28.22 A cm−2 K−2, which is very close to the theoretical value for n-type GaN/Pt contacts. As expected, the presence of defect states with different trap energy levels has a noticeable impact on the device electrical characteristics.

Phd by thesis

Abstract: Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Waste Heat Recovery Technologies and Applications

Abstract: Horizon 2020 Project “Design for Resource and Energy efficiency in CerAMic Kilns- DREAM Project (Grant No: 723641), Horizon 2020 Industrial THERMal energy recovery conversion and management (Grant No:680599) and ESPRC (Grant No: EP/P004636/1)

Density-matrix theory of semiconductor lasers with relaxation broadening model - Gain and gain-suppression in semiconductor lasers

Abstract: The density-matrix theory of semiconductor lasers with relaxation broadening model is finally established by introducing theoretical dipole moment into previously developed treatments. The dipole moment is given theoretically by the k . p method and is calculated for various semiconductor materials. As a result, gain and gain-suppression for a variety of crystals covering wide wavelength region are calculated. It is found that the linear gain is larger for longer wavelength lasers and that the gain-suppression is much larger for longer wavelength lasers, which results in that single-mode operation is more stable in long-wavelength lasers than in shorter-wavelength lasers, in good agreement with the experiments.

Band Gaps of InN and Group III Nitride Alloys

Abstract: We review the fundamental band gaps of wurtzite InN and group III nitride ternary alloys in the light of the recent discovery of the narrow band gap of InN. The results on the composition, temperature and hydrostatic pressure dependence of the band gaps of these alloys are summarized and discussed. The role of the Burstein–Moss shift for the accurate determination of the band gap is emphasized. The impact of the narrow band gap of InN on new device applications of group III nitrides is briefly discussed.