摘要:

We show that three‐dimensional arrays of electrically small, anisotropic particles are excellent media for wave‐mixing processes at microwave and millimeter wavelengths. Electrostrictive torques rotate the particles in such a way as to form orientational index gratings that can control the attributes of microwave or millimeter wave radiation. Theory asserts that this medium is highly favorable for phase conjugation via quasidegenerate four‐wave mixing at these wavelengths.

ISSN:0021-8979    

DOI:10.1063/1.350542

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

This paper describes the fabrication and evaluation of dielectric‐base transistors having high‐TcYBa2Cu3O7−xelectrodes with NdGaO3low‐permittivity barriers on SrTiO3high‐permittivity substrates. The YBa2Cu3O7−x/NdGaO3/SrTiO3heterostructures were made by laser ablation. Nb base electrodes were sputtered on the back of the SrTiO3substrate. The device showed transistor characteristics with voltage and current gains exceeding unity at 4.2 K. The collector current density was about 10 A/cm2at a collector voltage of 20 V, four orders of magnitude larger than that obtained for devices having no artificial barriers.

ISSN:0021-8979    

DOI:10.1063/1.350543

出版商:AIP    

年代:1992

数据来源: AIP

摘要:

The recently developed technique of real time spectroscopic ellipsometry (SE) has been applied to characterize the nucleation of diamond onc‐Si by W filament‐assisted chemical vapor deposition, leading to improved control over the process. Specifically, techniques are developed which minimize W contamination at the diamond/substrate interface; calibrations are performed which determine the temperature of the top ∼250 A˚ of the substrate under growth conditions; and alterations in gas flow conditions are implemented in response to diamond growth for a reduced induction time. With these procedures in place, real time SE provides the induction time, nucleation density, and mass thickness, and is in quantitative agreement withexsituscanning electron microscopy.

ISSN:0021-8979    

DOI:10.1063/1.350544

出版商:AIP    

年代:1992

数据来源: AIP