摘要:

One‐side bound states are very important in vertical resonant tunneling devices which contain either lightly doped spacers or a small band‐gap pseudomorphic layer adjacent to the barriers. By a proper choice of the boundary conditions, these states are modeled by stationary wave functions which contain the relevant information of the quasi‐two‐dimensional system under steady‐state conditions. In particular, the wave functions allow the calculation of their contributions to the self‐consistent charge density and the electrical current. In qualitative agreement with experimental results, it is demonstrated that the main resonant features of the current–voltage characteristic of these devices are due to resonant tunneling from an emitter two‐dimensional electron gas. Finally, the proposed model is compared with a previous picture of other authors. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360196

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Sr2(AlTa)O6thin films (2000–3000 A˚) have been deposited on MgO (001) substrates using pulsed laser deposition (PLD). X‐ray‐diffraction analysis shows that the Sr2(AlTa)O6grows with thecaxis highly oriented normal to the substrate plane and very good in‐plane epitaxy. The subsequently deposited YBa2Cu3O7−xfilms using PLD on Sr2(AlTa)O6buffered MgO substrates exhibit excellent epitaxial growth with a narrow rocking curve width and a small &fgr; scan peak width. The critical temperatureTc0of 90–92 K has been achieved reproducibly and the critical current density is over 2.7×106A/cm2at 77 K. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360197

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effect of the nitrogen partial pressure on the deposition rate of nickel lines produced by laser‐induced chemical vapor deposition (LCVD) from nickel tetracarbonyl, Ni(CO)4, was investigated and discussed by Boughaba and Auvert on the basis of the Langmuir–Hinshelwood model valid for heterogeneous chemical reactions with competitive adsorption of reactant gases on the surface. From these experimental results, it can be demonstrated that the adsorption energy of nitrogen molecules on the nickel surface is negligible; as a result, it can be concluded that the residence time of nitrogen molecules as adspecies on the polycrystalline nickel surface is negligible, and the adsorption of nickel molecules on the nickel surface does not occur. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360198

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

By discussing the three main comments on our paper, we demonstrate that our experimental conditions: low gas pressure and reaction area radius below the mean free path in the gas phase, are only compatible with a modification of the reaction surface without any diffusion limited process. ©1995 American Institute of Physics.

ISSN:0021-8979    

DOI:10.1063/1.360199

出版商:AIP    

年代:1995

数据来源: AIP