Comparative study of n-p GaN/SiC heterojunction and p-n 6H-SiC homojunction diodes

A comparative study between GaN/SiC heterojunction and 6H-SiC homojunction diodes has been performed to understand the physical properties of n-p GaN/SiC heterojunction interface. The 6H-SiC homojunction diodes presented typical I-V characteristics with satisfactory breakdown voltage (≅-800 V), however, the GaN/SiC heterojunction diodes showed an abnormal low forward turn-on voltage (≅1.8 V). The presence of a deep-level 1 eV below the p-SiC conduction band, is probably responsible for a tunneling- assisted current at low forward voltages, due to a high concentration of interface defects

Morphological and Optical properties of ZnO thin films grown on Si and ITO glass substrates

International audienceIn this study, ZnO thin films have been electrodeposited from zinc nitrate solution without using any catalyst, additive or seed layer on two kinds of substrates (Si and ITO glass).Using cyclic voltammetry and chronoamperometry, it was shown that the mechanism of ZnO deposition strongly depends on the substrate used and its overpotential for nitrate reduction. On Si, the nitrate reduction into nitrite occurs before that of Zn2+. This reaction induces an increase of the local pH leading to ZnO precipitation. In contrast on ITO, the Zn2+ reduction brings first metallic Zn deposition, which is then chemically oxidized by nitrate into ZnO phase. The effect of deposition time on morphology, structure and photoluminescence properties was studied using X-ray diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence (PL) measurements.The chemical nature of the substrate has no influence on the orientation of nanorods, but really impacts their morphology and the optical emission properties. X-ray diffraction analysis always revealed ZnO wurtzite phase with a (002) preferential orientation enhanced with increasing deposition time. A well-defined ZnO morphology was generated under -1.4 V for 60 min on Si and ITO glass. ZnO nanorods that composed the nanoflowers grown on ITO glass tend to be shorter, wider, with higher aspect ratio than on Si. ZnO nanostructures prepared on ITO showed an intense UV emission without spreading in the visible region, thus demonstrating the formation of a defect free structure

How Does FDI React to Corporate Taxation?

Based on a panel of bilateral FDI flows among 11 OECD countries over 1984–2000, we show that, although agglomeration-related factors are strong determinants of FDI, tax differentials also play a significant role in understanding foreign location decisions. We further investigate non-linearities in the impact of tax differentials, and explore the impact of tax schemes. Our results are consistent with the imperfect competition literature which underscores the possibility of tax differentials across countries in equilibrium. Copyright Springer Science + Business Media, Inc. 2005Tax competition, Foreign Direct Investment,