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1.
The thermal stability and measurement temperature dependence of Schottky contact characteristics on n-GaN using a W2B5/Ti/Au metallization scheme was studied using current-voltage (I-V), scanning electron microscopy (SEM) and Auger electron spectroscopy (AES) measurements. The elemental profile obtained from samples annealed at 350 °C showed some titanium diffusion into the gold layer but little other difference from the as-deposited wafer. Annealing at 700 °C produced significant diffusion of titanium. The Schottky barrier height increased with anneal temperature up to 200 °C, reaching a maximum value of 0.65 eV, but decreased at higher annealing temperatures. The reverse breakdown voltage from diodes fabricated using the W2B5-based contacts showed a similar dependence. The reverse current magnitude was larger than predicted by thermionic emission alone. The barrier height showed only minor changes with measurement temperature up to 150 °C. 相似文献
2.
Summary Heterobimetallic complexes of the types [Cp2Ti(-EAr)2-M(dppe)] (ClO4)2 [(1)–(4); M, E = Ni, Te (1); Ni, Se (2); Pt, Te (3); Pt, Se (4); Ar = Ph (a), C6H4-4-Me (b), C6H4-4-OMe (c), C6H4-4-OEt (d)] and [Cp2Ti(-TeAr)2-MCl 2] [M = Pd (5), Pt (6)] were obtained by the reactions of Cp2Ti(EAr)2 with M(dppe)(ClO4)2 and M(PhCN)2Cl2, respectively. While (1), (5) and (6) are stable in the solid state as well as in solution, (2)–(4) undergo dissociation to M(dppe)(EAr)2 and Cp2Ti(ClO4)2 in solution, as shown by multinuclear (31P{1H},195Pt{1H}, 125Te{1H}) n.m.r. studies. The reaction of Cp2Ti(SeAr)2 with M(PhCN)2Cl2, however, leads to the formation of Cp2TiCl2 and a polymeric material [M(SeAr)2]
n
. 相似文献
3.
V. K. Ahluwalia K. Bhat Chandra Prakash Manjula Khanna 《Monatshefte für Chemie / Chemical Monthly》1981,112(1):119-124
A convenient synthesis of linear pyranocoumarins, viz., 8,8-dimethyl-2H,8H-benzo[1,2-b; 5,4-b]dipyran-2-one (xanthyletin,1) and 8,8-dimethyl-3-phenyl-2H,8H-benzo[1,2-b; 5,4-b]dipyran-2-one (3-phenylxanthyletin,2) is described. The key steps are blocking the 8-position of appropriate 7-hydroxy-2H-1-benzopyran-2-one derivatives with iodine and 1,1-dimethyl-2-propynylation followed by cyclisation.
Ein einfacher Syntheseweg zu linearen Pyranocumarinen. Xanthyletin und 3-Phenylxanthyletin
Zusammenfassung Es wird ein vorteilhafter Weg zur Synthese von linearen Pyranocumarinen am Beispiel von Xanthyletin und 3-Phenylxanthyletin gezeigt. Das Syntheseprinzip besteht in einer Blockierung der 8-Position des entsprechenden 7-Hydroxy-2H-1-benzopyran-2-ons mit Jod und einer 1,1-Dimethyl-2-propinylierung mit nachfolgender Cyclisierung.相似文献
4.
Lanthanum, cerium, neodymium, samarium, europium, gadolinium, dysprosium, erbium, ytterbium, lutetium and yttrium have been determined in 8 international rock standards by inductively coupled plasma atomic emission spectrometry (ICP-AES) without prior ion-exchange separation and preconcentration. The results for La, Ce, Nd, Eu, Dy, Yb and Y were in good agreement with the reported values, whereas those for Sm, Gd, Er and Lu were less accurate. However, the results for Sm, Gd, Er and Lu can also be used for studies of petrogenesis. 相似文献
5.
C.A. Cody R.C. Levitt R.K. Khanna Philip J. Miller 《Journal of solid state chemistry》1978,26(3):293-309
The infrared and Raman spectra of NaH3(SeO3)2 and NaD3(SeO3)2 have been recorded from 24 to 300°K. The interpretation, assignments, and analysis of the spectral studies are presented on the paraelectric α phase (proton disordered), ferroelectric β phase (proton ordered) and ferroelectric γ phase (proton ordered). A discussion of a newly proposed proton-triggered phase transition mechanism and a possible origin of the hydrogen-bonded OH stretching region of KH2PO4-type ferroelectrics is given. 相似文献
6.
7.
Spin configuration of Gd13 clusters 总被引:1,自引:0,他引:1
8.
9.
Summary A series of square planar complexes of the type [PdX2L2] where X=Cl, Br, I; L=telluracyclopentane (tcp), telluracyclohexane (tch) or benzotelluracyclopentane (btp) have been synthesised. The complexes were characterised by far-i.r., n.m.r. and u.v.-vis. spectroscopy. The data implytrans-geometries except for the complex [PdCl2(tch)2] where a mixture ofcis- andtrans-isomers is obtained. 相似文献
10.
Y. P. Khanna E. M. Pearce 《Journal of polymer science. Part A, Polymer chemistry》1981,19(11):2835-2840
The flammability of poly(1,3-phenylene isophthalamide) and poly(chloro-2,4-phenylene isophthalamide) was measured by the oxygen index method. The chloro polyamide had reduced flammability shown by a 10–15 higher oxygen index. Analysis of the chars of the two polymers at 700°C by thermogravimetry (TGA) and elemental analysis showed that the chlorine caused a significant increase in the retention of C, H, N, and O in the pyrolysis residue. Most of the chlorine in the chloro polyamide, however, was lost by 700°C. Based on these results, we have suggested that the chlorine imparts flame retardancy by a combination of vapor- and condensed-phase mechanisms. The origin of condensed-phase activity is discussed. 相似文献