Investigation of iodine as a donor in MBE grown Hg1−xCdxTe

N-type Hg_1−xCd_xTe layers with x values of 0.3 and 0.7 have been grown by molecular beam epitaxy using iodine in the form of CdI₂ as a dopant. Carrier concentrations up to 1.1 × 10¹⁸ cm⁻³ have been achieved for x = 0.7 and up to 7.6 × 10¹⁷ cm⁻³ for x=0.3. The best low temperature mobilities are 460 cm²/(Vs) and 1.2 × 10⁵ cm²/(Vs) for x=0.7 and x=0.3, respectively. Using CdI₂ as the dopant modulation doped HgTe quantum well structures have been grown. These structures display very pronounced Shubnikov-de Haas oscillations and quantum Hall plateaus. Electron densities in the 2D electron gas in the HgTe quantum well could be varied from 1.9 × 10¹¹ cm⁻² up to 1.4 × 10¹² cm⁻² by adjusting the thicknesses of the spacer and doped layer. Typical mobilities of the 2D electron gas are of the order of 5.0 × 10⁴ cm²/(Vs) with the highest value being 7.8 × 10⁴ cm²/(Vs).     

Up Scope

The scope of the magazine is being expanded to incorporate reliability and dependability concerns and its readership will include members of the IEEE Reliability Society. This expansion is appropriate because the requirements for a system to be reliable, safe, secure (i.e. its dependability or trustworthiness attributes) often need to be considered together in order to achieve the desired result.     

Controlling micro‐ and nanofibrillar morphology of polymer blends in low‐speed melt spinning process. Part II: Influences of extrusion rate on morphological changes of a PLA/PVA blend through a capillary die

The effects of the extrusion rate on the morphological changes of poly(lactic acid) (PLA)/poly(vinyl alcohol) (PVA) blend through a capillary die were investigated. In this study, the extrusion rate or mass flow rate is altered from 0.5 g min^?1 to 2 g min^?1 with an increment of 0.5 g min^?1. The PLA/PVA blend with a composition of 30/70 (wt %) exhibits a particle matrix morphology with dispersed PLA droplets within the PVA matrix. It is found that, the spherical or ellipsoidal dispersed PLA droplets are elongated and coalesced into rod‐like or longer ellipsoidal droplets when they pass through the capillary die. When the extrusion rate increases, the coalescence between the large PLA droplets occurs more intense. However, the changes of the extrusion rate have no strong effect on the coalescence of small droplets having diameter less than about 150 nm. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44257.     

Shubnikov-De Haas Oscillations Caused by a Two-Dimensional Leakage Channel on Silicon Mosfets Induced by Electron Irradiation

A possible failure mechanism of n-channel MOSFETs exposed to ionizing radiation are leakage currents between source and drain. This leakage begins to occur at relatively low radiation doses, and can seriously degrade the performance of an otherwise hardened CMOS device. In the present paper, we demonstrate by the observation of quantum oscillations in the magnetoresistance that by room temperature irradiation with high energy electrons an inversion layer is generated under the field oxide, which gives rise to leakage currents. Magnetoresistance oscillations may be observed, if in a degenerate electron gas the carrier mobility is sufficiently high to allow quantization of the electron movement in a magnetic field and the thermal energy is much smaller than the cyclotron energy. This oscillatory behaviour of the electrical resistance as a function of a magnetic field - the Shubnikov-de Haas effect - is a valuable tool to investigate the electronic parameters of bulk semiconductors and surface channels. Such experiments not only give firm evidence about the existence of a bypass inversion layer, but also yield information about the carrier density in the radiation induced channel. It turns out that the electrons behave like a two-dimensional free electron gas the density of which is independent of the gate voltage. Moreover, the experiments give knowledge about the influence of trapped charges, caused by the irradiation at the interface.     

New Challenges for the New Year

You've heard from me in this space before, but this is my first column as IEEE Security & Privacy's editor in chief. I feel both honored and privileged to have the opportunity to assume this responsibility. George Cybenko, as both the driving force behind the magazine's creation and its EIC for the first four years, is a hard act to follow. But because he created such a strong base for the magazine, I'm hoping it won't be a difficult act to continue. You can expect the mix of articles, departments, and special issues on current topics to continue. You'll see some new names in the masthead as we replace those rotating off the editorial board; this is a normal process for all IEEE publications. We'll continue to strive for fresh and interesting material to keep you at the forefront of technology and issues in security and privacy.     

Processing of ZrC–Mo Cermets for High-Temperature Applications, Part I: Chemical Interactions in the ZrC–Mo System

The chemical compatibility of ZrC and Mo was investigated in carburizing and carbon-free environments at temperatures from 1700° to 2200°C. Heating in the carburizing atmosphere resulted in the complete reaction of Mo with C, while the carbon-free atmosphere resulted in retained metallic phase with a maximum of 13.8 mol% Mo₂C formed. The presence of Mo₂C was not detected at 2100°C in the carbon-free atmosphere, confirming the existing phase equilibria in the Zr–Mo–C system. Heat treatments in the carbon-free atmosphere also showed liquid formation at 2200°C, as evident from microstructure analysis. Liquid formation was consistent with the interaction between Mo and Mo₂C. The liquid was found to comprise at least 7 vol% of the total component, based on a phase diagram for the Mo–C system. The formation of a liquid should allow for the processing of ZrC–Mo cermets by liquid-phase pressureless sintering.