Time filter

Source Type

Messai Z.,Prisme Institute | Messai Z.,Laboratoire Optoelectronique et Composants | Messai Z.,University of Bordj Bou Arréridj | Ouennoughi Z.,Laboratoire Optoelectronique et Composants | And 6 more authors.
Applied Surface Science | Year: 2010

In this paper we study nanocrystalline zinc oxide thin films produced by oxidation of electrodeposited zinc nanolayers on a monocrystalline p-Si(1 1 1) substrate. The electrolyte used is ZnCl2, an aqueous solution of 4 × 10-2 mol/l concentration. Several deposits were made for various current densities, ranging from 13 mA/cm2 to 44 mA/cm 2, flowing through the solution at room temperature. A parametric study enabled us to assess the effect of the current density on nucleation potential and time as well as zinc films structure. The grazing incidence X-ray diffraction (GIXD) revealed that both Zn and ZnO films are polycrystalline and nanometric. After 1-h oxidation of zinc films at 450 °C in the open air, the structural analyses showed that the obtained ZnO films remained polycrystalline with an average crystal size of about 47 nm and with (1 0 0), (0 0 2) and (1 0 1) as preferential crystallographic orientations. © 2010 Elsevier B.V.

Toumi S.,Laboratoire optoelectronique et composants | Ouennoughi Z.,Laboratoire optoelectronique et composants | Strenger K.C.,Fraunhofer Institute for Integrated Systems and Device Technology | Frey L.,Fraunhofer Institute for Integrated Systems and Device Technology
Solid-State Electronics | Year: 2016

Current conduction mechanisms through a Metal-Oxide-Semiconductor structure are characterized via Fowler-Nordheim (FN) plots. The extraction of the FN parameters like the electron/hole effective mass in oxide . mox and in semiconductor . msc , the barrier height at the semiconductor-oxide interface . ϕ(symbol)B , and the correction oxide voltage . Vcorr for a MOS structure is made using a vertical optimization process on the current density without any assumption about . ϕ(symbol)B or . mox . An excellent agreement is obtained between the FN plots calculated with the FN parameters extracted using a vertical optimization process with the experimental one. © 2016 Elsevier Ltd.

Sellai A.,Sultan Qaboos University | Ouennoughi Z.,Laboratoire Optoelectronique et Composants | Le Thanh V.,CNRS Interdisciplinary Center on Nanoscience in Marseille | Petit M.,CNRS Interdisciplinary Center on Nanoscience in Marseille | And 2 more authors.
Proceedings of the Mediterranean Electrotechnical Conference - MELECON | Year: 2012

I-V and C-V measurements performed on Au/Mn 5Ge 3/n-Ge structures, prepared for spintronic applications, are presented and analysed over a wide range of temperatures (50 K-300 K) with the goal of elucidating the prevailing conduction mechanism(s). The effects of image force lowering and recombination in the depletion region on the measured current are shown to be of little significance and cannot acceptably explain the drawbacks that arise when a pure thermionic emission model is used in analyzing the temperature dependence of the obtained electrical characteristics. Considering, however, the eventual contribution of thermally assisted tunneling to the current generating mechanism could explain the departure from pure thermionic emission. Thermionic field emission seems indeed to explain better our I-V data and the temperature dependence of related parameters. Also, the C-V measurements reveal a nonuniform carrier distribution with manifest peaks in the doping profile, possibly signifying the existence of charge accumulation and trap centers. © 2012 IEEE.

Latreche A.,Laboratoire Optoelectronique et Composants | Ouennoughi Z.,Laboratoire Optoelectronique et Composants | Sellai A.,Sultan Qaboos University | Weiss R.,FIIS | Ryssel H.,FIIS
Semiconductor Science and Technology | Year: 2011

The electrical characteristics of ion-implanted guard rings for molybdenum (Mo) Schottky diodes on 4H-SiC are analyzed on the basis of the standard thermionic emission model and the assumption of a Gaussian distribution of the barrier height. For edge termination, high-resistivity guard rings manufactured by carbon and aluminum ion-implanted areas were used. Extractions of barrier heights of molybdenum on silicon carbide (4H-SiC) Schottky diodes have been performed on structures with various gate metallization, using both current-voltage-temperature (I-V-T) and capacitance-voltage (C-V) measurements. Characteristic features of the Schottky barrier height (SBH) are considered in relation to the specific dose of the carbon- or aluminum-implanted guard ring. Contacts showed excellent Schottky behavior ideality factors between 1.02 and 1.24 in the range of 303-473 K. The measured SBHs were between 0.92 and 1.17 eV in the same temperature range from I-V-T characteristics. The variations in the barrier height, which is significantly temperature- and implantation-dose- dependent, are well fitted to a single Gaussian distribution function. Experimental results agree reasonably well by using this approach, particularly for carbon implantation dose of 1.75 × 1014 cm-2, and a mean barrier height () of 1.22 eV and zero bias standard deviation σ0 = 0.067 V have been obtained. Furthermore, the modified Richardson plot according to the Gaussian distribution model resulted in a mean barrier height () and a Richardson constant (A*) of 1.22 eV and 148 A cm-2 K-2, respectively. The A* value obtained from this plot is in very close agreement with the theoretical value of 146 A cm -2 K-2 for n-type 4H-SiC. Therefore, it has been concluded that the temperature dependence of the forward (I-V) characteristics of the Mo/4H-SiC contacts can be successfully explained on the basis of a thermionic emission conduction mechanism with Guassianly distributed barriers. © 2011 IOP Publishing Ltd.

Latreche A.,University of Bordj Bou Arréridj | Ouennoughi Z.,Laboratoire Optoelectronique et Composants
International Journal of Numerical Modelling: Electronic Networks, Devices and Fields | Year: 2015

In this study, we show clearly why unexpected observations have been reported in the current-voltage curves of Schottky diodes, containing barrier inhomogeneities generated by using the analytical results based on a Gaussian distribution model of barrier heights. The Chand's calculations have shown that the current (saturation current) at low temperatures may exceed the current (saturation current) at high temperatures when the effective barrier height is calculated from an appropriate integral with integration limits -∞ and +∞. In this new study, we show that the method followed by Chand to remove these anomalies is not accurate enough. We prove that the origin of these anomalies stems from the nature of a proper function f(φ) that moves to the negative barrier heights and takes large value of the integral at low temperatures than at high temperatures when it has large standard deviation (σ) and the discrepancies are not due to the integration limits as Chand concluded. In order to obtain results consistent with the thermionic emission-diffusion theory, the standard deviation must have lower values. Copyright © 2014 John Wiley & Sons, Ltd.

Ouennoughi Z.,Laboratoire Optoelectronique et Composants | Toumi S.,FIIS | Weiss R.,Laboratoire Optoelectronique et Composants
Physica B: Condensed Matter | Year: 2014

In the present work we investigate the forward current-voltage (I-V) characteristics, over a wide temperature range 298-498 K, of Mo/4H-SiC Schottky diode for which aluminum ion implantation was used to create the high resistivity layer forming the guard ring. The (I-V) analysis based on Thermionic Emission (TE) theory shows a decrease of the barrier height φBand an increase of the ideality factor n when the temperature decreases. These anomalies are mainly due to the barrier height inhomogeneities at the metal/semiconductor interface as we get a Gaussian distribution of the barrier heights when we plot the apparent barrier height φapversus q/2kT. The mean barrier height and the standard deviation obtained values are φ¯B0=1.160 eV and σ0=88.049 mV, respectively. However, by means of the modified Richardson plot Ln(Is/T2)-(q2σ02/2k2T2) versus q/kT, the mean barrier height and the Richardson constant values obtained are φ¯B0=1.139 eV and A∗=129.425 A/cm2K2, respectively. The latter value of φ¯B0matches very well with the mean barrier height obtained from the plot of φapversus q/2kT. The Richardson constant is much closer to the theoretical value of 146 A/cm2K2. The series resistance Rsis also estimated from the forward current-voltage characteristics of Mo/4H-SiC Schottky contact. This parameter shows strong temperature dependence. The T0effect is validated for the 298-498 K temperature range for the used Schottky diode and provides a clear evidence for the barrier inhomogeneity at the Mo/4H-SiC interface. Finally, we note the impact of the implantation process as well as the choice of the used ion on the characterized parameters of the Schottky contact. © 2014 Elsevier B.V.

Latreche A.,University of Bordj Bou Arréridj | Ouennoughi Z.,Laboratoire Optoelectronique et Composants | Weiss R.,FIIS
Semiconductor Science and Technology | Year: 2016

The inhomogeneous parameters of Mo/4H-SiC Schottky barrier diodes were determined from current-voltage (I-V) characteristics in the temperature range of 303-498 K by using a general approach for the real Schottky diode. In this approach the total series resistances is divided into two resistances; the first one (R P) is the sum of the series resistances (r) of the particular diodes connected in parallel and the second is the common resistance (R C) to all particular diodes. The mean barrier height and the standard deviation (σ) decrease linearly with decreasing temperature and they are between the values for the diodes with the two limiting cases; no current spreading and full current spreading. The series resistance R C increases, while the series resistance R P slightly decreases with decreasing temperature. © 2016 IOP Publishing Ltd.

Latreche A.,University of Bordj Bou Arréridj | Ouennoughi Z.,Laboratoire Optoelectronique et Composants
Semiconductor Science and Technology | Year: 2013

We present a simple method for analysing the tunnelling current through Schottky barrier diodes on SiC, based on the modified Airy function (MAF) approach. The MAF method is accurate for linear-shaped barriers which is the case for the top of the Schottky barrier diodes. The results have been compared with those obtained by the conventional Wentzel-Kramers-Brillouin (WKB). This study proves that the WKB method is valid for the Schottky barrier diodes with and without the incorporation of Schottky barrier lowering under low or high bias voltage. © 2013 IOP Publishing Ltd.

Boussouar L.,Laboratoire Optoelectronique et Composants | Ouennoughi Z.,Laboratoire Optoelectronique et Composants | Rouag N.,Laboratoire Optoelectronique et Composants | Sellai A.,Sultan Qaboos University | And 2 more authors.
Microelectronic Engineering | Year: 2011

Using current-voltage measurements, we have investigated the electrical behavior of molybdenum on 4H-SiC Schottky diodes of various areas and having different edge terminations consisting of high resistivity guard rings manufactured by carbon ion-implantation. Both forward and reverse electrical characteristics of Schottky contacts indicated a presence of inhomogeneities. The forward I-V characteristics have been primarily analyzed within the framework of a standard thermionic emission theory. Schottky-barrier heights and ideality factors are found to appreciably vary from diode to diode. A more general model which takes into account the inhomogeneity of the Schottky barrier has been then used to extract the parameters pertinent to the barrier height distribution. The description of the experimental results using Tung's model allowed us to determine the value of the average laterally homogeneous SBH barrier height between 1.2 and 1.39 eV for Mo/4H-SiC Schottky diodes. The patch's properties (the number of patches, the patch strength and the local series resistance) were also obtained from the fit to the experimental I-V characteristics of the current through "patchy" diodes. The obtained results are best described with this extended "pinch off" model. With respect to the reverse characteristics, the remarked absence of a non-saturating behavior as a function of bias in the experimental reverse-bias branch may well be attributed to the presence of defects and/or inhomogeneous Schottky barrier heights, associated with the non-ideal contacts. © 2010 Elsevier B.V. All rights reserved.

Loading Laboratoire Optoelectronique et Composants collaborators
Loading Laboratoire Optoelectronique et Composants collaborators