A study of the rectifying behaviour of aniline green-based Schottky diode

An Al/aniline green (AG)/Ga₂Te₃ device was fabricated and the current-voltage (I-V), capacitance-voltage (C-V) and capacitance-frequency (C-f) characteristics of the device have been investigated at room temperature. The values of the ideality factor, series resistance and barrier height obtained from Cheung and Norde methods were compared, and it was seen that there was an agreement with each other. It was seen that the forward bias current-voltage characteristics at sufficiently large voltages has shown the effect of the series resistance. In addition, it was seen from the C-f characteristics that the values of capacitance have been decreased towards to the high frequencies. The higher values of capacitance at low frequencies were attributed to the excess capacitance resulting from the interface states in equilibrium with the Ga₂Te₃ that can follow the ac signal.     

Fabrication of Al/MgO/C and C/MgO/InSe/C tunneling barriers for tunable negative resistance and negative capacitance applications

In this work, the design and characterization of magnesium oxide based tunneling diodes which are produced on Al and InSe films as rectifying substrates are investigated. It was found that when Al thin films are used, the device exhibit tunneling diode behavior of sharp valley at 0.15 V and peak to valley current ratio (PVCR) of 11.4. In addition, the capacitance spectra of the Al/MgO/C device show a resonance peak of negative capacitance (NC) values at 44.7 MHz. The capacitance and resistance–voltage characteristics handled at an ac signal frequency of 100 MHz reflected a build in voltage (V_bi) of 1.29 V and a negative resistance (NR) effect above 2.05 V. This device quality factor (Q)–voltage response is ~10⁴. When the Al substrate is replaced by InSe thin film, the tunneling diode valley appeared at 1.1 V. In addition, the PVCR, NR range, NC resonance peak, Q and V_bi are found to be 135, 0.94–2.24 and 39.0 MHz, ~10⁵ and 1.34 V, respectively. Due to the wide differential negative resistance and capacitance voltage ranges and due to the response of the C/MgO/InSe/C device at 1.0 GHz, these devices appear to be suitable for applications as frequency mixers, amplifiers, and monostable–bistable circuit elements (MOBILE).     

Effect of an organic compound (Methyl Red) interfacial layer on the calculation of characteristic parameters of an Al/Methyl Red/p-Si sandwich Schottky barrier diode

An Al/Methyl Red/p-Si sandwich Schottky barrier diode (SBD) has been fabricated by adding a solution of the organic compound Methyl Red in chloroform onto a p-Si substrate, and then evaporating the solvent. Current-voltage (I-V) measurements of the Al/Methyl Red/p-Si sandwich SBD have been carried out at room temperature and in the dark. The Al/Methyl Red/p-Si sandwich SBD demonstrated rectifying behavior. Barrier height (BH) and ideality factor values of 0.855 eV and 1.19, respectively, for this device have been determined from the forward-bias I-V characteristics. The Al/Methyl Red/p-Si sandwich SBD showed non-ideal I-V behavior with the value of ideality factor greater than unity. The energy distribution of the interface state density determined from I-V characteristics increases exponentially with bias from 3.68 × 10¹² cm^− 2 eV^− 1 at (0.81 − E_v) eV to 9.99 × 10¹³ cm^− 2 eV^− 1 at (0.69 − E_v) eV.     

Ei Compendex数据库收录东北电力大学论文统计分析

本文对以东北电力大学署名发表的论文被美国Ei Compendex数据库收录情况进行了统计,通过收录论文的数量、作者学科分布、作者单位署名、论文发表的期刊分布、文献类型及语言种类等角度进行了分析,给出了提高科技论文Ei收录率的建议。     

2000年Ei光盘数据库收录我国中文期刊论文统计分析

通过对2000年美国《工程索引（Ei）》光盘数据库进行检索，得出被《Ei》收录的我国中文科技期刊的种数、收文数及其所属学科的分布情况，统计分析的结果为我国科技人员向《Ei》收录的我国中文科技期刊投稿提供科学依据。     

Pressurized heavy water reactor fuel behaviour in power ramp conditions

In order to check and improve the quality of the Romanian CANDU fuel, an assembly of six CANDU fuel rods has been subjected to a power ramping test in the 14 MW TRIGA reactor at INR. After testing, the fuel rods have been examined in the hot cells using post-irradiation examination (PIE) techniques such as: visual inspection and photography, eddy current testing, profilometry, gamma scanning, fission gas release and analysis, metallography, ceramography, burn-up determination by mass spectrometry, mechanical testing. This paper describes the PIE results from one out of the six fuel rods. The PIE results concerning the integrity, dimensional changes, oxidation, hydriding and mechanical properties of the sheath, the fission-products activity distribution in the fuel column, the pressure, volume and composition of the fission gas, the burn-up, the isotopic composition and structural changes of the fuel enabled the characterization of the behaviour of the Romanian CANDU fuel in power ramping conditions performed in the TRIGA materials testing reactor.     

Preparation of location-specific thin foils from Fe–3% Si bi- and tri-crystals for examination in a FEG-STEM

Bi-crystals and tri-crystals of a nominal Fe–3% Si (wt%) of well-defined orientations have been grown using a floating-zone technique with optical heating. The manufacture of these unique crystals and the preparation technique involved in harvesting thin foils from specific locations for transmission electron microscopy are described in detail. In particular, the grain boundary triple junction has been extracted from the tri-crystal and examined in high-resolution aberration-corrected FEG-STEM instruments. To achieve the necessary resolution, the foils have to be uniformly thin, in the range 50–100 nm over large areas of the specimen. For ferromagnetic materials, there are further challenges arising from the magnetic field interaction, with the electron beam placing significant demands on the aberration correction system. One way to minimise this interaction is to reduce the total mass of magnetic material. To achieve this, an in situ focused ion beam lift-out technique has been combined with an additional precision ion-polishing stage to reproducibly provide thin-foil specimens suitable for high-resolution EELS and EDX analysis. Examination of the foils reveals that the final precision ion-polishing stage removes residual damage arising from the use of focused ion beam milling procedures.     

AMS radiocarbon dating of medieval textile relics: The frocks and the pillow of St. Francis of Assisi

Since natural textiles usually originate from short-lived organisms, they can represent a useful material to date samples from historical periods with a good accuracy.In this work, we present a set of radiocarbon measurements on medieval textile relics: two woollen habits and a pillow traditionally associated with St. Francis of Assisi, the saint patron of Italy. The strategy in choosing samples for radiocarbon dating is first discussed and the procedures for measurements - performed at the 3 MV Tandetron accelerator of Laboratorio di Tecniche Nucleari per i Beni Culturali (LABEC), Florence - are described; AMS results for the two frocks showed that only one of them, presently kept in the church of St. Francis in Cortona, is compatible with the Saint’s period of life, as is the pillow also kept in Cortona. Another frock attributed to St. Francis appears to date from at least 80 years after his death. However, the goal of these measurements was not a bare authentication/disconfirmation of the relics; they just represent an example of how scientific analysis can integrate with humanistic studies. Indeed, AMS results, combined with a thorough analysis of the textiles typologies, confirmed the historical hypotheses based on documentary studies and on tradition. The overall conclusions contributed to the decisions taken for conservation, and have as a whole enhanced the religious importance of the relics.     

Temperature dependence of barrier height parameters of inhomogeneous Schottky diodes

We have shown by numerical simulations of I-V-T curves that the ideality factor of inhomogeneous Schottky diodes does not increase for decreasing temperature to such extent as is commonly observed for Schottky diodes in experiment. The main consequence of such a result is that in spite of the fact that the barrier height inhomogeneities fullfil the conditions for barrier height lowering for decreasing temperature they might not be a general or the only reason for occuring of this effect in experimental structures. We found out much slower ideality factor temperature dependence than reported in the literature and the dependence was even not monotonous for simulation conditions used. We conclude that some other reason as barrier inhomogeneity is responsible for ideality factor temperature dependence.     

The electrical characteristics of Sn/methyl-red/p-type Si/Al contacts

The junction characteristics of the organic compound methyl-red film (2-[4-(dimethylamino)phenylazo]benzoic acid) on a p-type Si substrate have been studied. The current-voltage characteristics of the device have rectifying behavior with a potential barrier formed at the interface. The barrier height and ideality factor values of 0.73 eV and 3.22 for the structure have been obtained from the forward bias current-voltage (I-V) characteristics. The interface state energy distribution and their relaxation time have ranged from 1.68 × 10¹² cm⁻² eV⁻¹ and 1.68 × 10⁻³ s in (0.73-E_v) eV to 1.80 × 10¹² cm⁻² eV⁻¹ and 5.29 × 10⁻⁵ s in (0.43-E_v) eV, respectively, from the forward bias capacitance-frequency and conductance-frequency characteristics. Furthermore, the relaxation time of the interface states shows an exponential rise with bias from (0.43-E_v) eV towards (0.73-E_v) eV.