摘要:

An enhanced leakage current through thin SiO2gate insulators following ion implantation of source/drain regions in self‐aligned gate complementary‐metal‐oxide semiconductors has been examined. The enhanced leakage current degrades insulator properties and is localized at the perimeter of the gate feature. A model of ion mixing between the gate material, oxide layer, and underlying silicon at the gate‐feature edge has been used to explain the degradation. The atomic weight of the implant species is critical, with heavier species like arsenic demonstrating a severe degree of degradation. Implantation of lighter species like boron results in minimal degradation at normal dose levels. The gate‐electrode material is also important. Electrodes formed with the highest‐atomic‐weight and density materials demonstrate the most degradation. Gate charging during the ion‐implantation process does not significantly impact the degree to which samples are degraded at the implant currents used in this work.

ISSN:0021-8979    

DOI:10.1063/1.344956

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new theory for the junction capacitance of mathematically abrupt diodes is presented. In contrast with previous theories, Fermi–Dirac statistics are applied, and instead of using a parabolic density of states, a more appropriate function can be taken into account as this is required for heavily doped material. The main approximation is that of constant quasi‐Fermi levels. Besides the study of symmetrical junctions, the behavior of asymmetrical abrupt junctions is both analyzed and explained. Anomalies resulting from the calculations are shown to be due to the mathematical discontinuity.

ISSN:0021-8979    

DOI:10.1063/1.344957

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Microwave‐detected optical response (MDOR) of YBa2Cu3O7−xand other oxide superconductor thin films is shown to yield information complementary to that provided by trasnport photoconductivity measurements. The MDOR technique yields a superposition of response from all illuminated portions of a sample, irrespective of the existence of a resistive macroscopic percolative current path. The response is found to be bolometric at temperatures for which resistance appears in transport measurements. At low temperatures MDOR results imply a nonbolometric response which in some respects is consistent with nonequilibrium quasiparticle concentration due to radiative pair breaking.

ISSN:0021-8979    

DOI:10.1063/1.344958

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Epitaxial thin films of YBaCuO have been prepared with (1) theaaxis perpendicular to (100) SrTiO3; (2) thecaxis perpendicular to (100) SrTiO3; and (3) the [110] axis perpendicular to (110) SrTiO3. Films were fabricated using a multilayer deposition technique involving three electron guns containing Y, BaF2, and Cu under a pressure of 5×10−5Torr of O2. As deposited films, which contained polycrystalline and amorphous regions, were later annealed in a furnace under a flowing O2‐H2O atmosphere. X‐ray diffraction patterns as well as scanning electron microscopy and high‐resolution electron microscopy images confirm that the films are highly oriented, essentially epitaxial. Thea‐axis oriented film exhibits zero resistance at 90 K and a critical current density of 2.9×106A/cm2at 4.2 K while thec‐axis oriented film exhibits aTcof 88 K and aJcof 0.9×107A/cm2at 4.2K; theJcvalues were determined magnetically. The [110]‐orientation film shows the sharpest transition with a transition width of 1 K and zero resistance at 85 K.

ISSN:0021-8979    

DOI:10.1063/1.344932

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

In this paper we study the low‐lying energy levels of Co2+and Fe2+in diluted magnetic semiconductors, such as Cd1−xCoxTe and Cd1−xCoxSe, and their iron‐based counterparts. In the first of these compounds, the magnetic ion sits on a site of symmetryTd, while in the second the symmetry is trigonal (C3v). We develop a formulation that permits a continuous variation fromTdtoC3vsymmetry. Comparison with experimental data in Cd1−xCoxSe shows that theC3vdistortion amounts to about 10% of the crystal potential at the Co2+site. Our study of the energy spectra of Fe2+inTdandC3vcrystal potentials reveals that, even in the cubic field, the levels exhibit an anisotropy which manifests itself in an anisotropy of the magnetizationMin the regime in whichMis not a linear function of the magnetic fieldB. The study includes all the levels in the lowest terms of the (3d)7and (3d)6configurations of Co2+and Fe2+, thus considerably extending work by previous authors. The calculations are carried out to second order in the spin‐orbit interaction and inBfor the lowest orbital states, and to first order inBfor the excited states. Thegfactors of all the levels are obtained including their anisotropy for the Co2+&Ggr;8states.

ISSN:0021-8979    

DOI:10.1063/1.344933

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Several Nd‐Fe‐B magnets were prepared by the liquid dynamic compaction (LDC) process, one of the newer rapid solidification techniques. The LDC processed magnets, when produced at low‐atomization gas pressures (coarse spray and low cooling rates), showed a dendritic structure and showed a mostly amorphous structure when produced at high gas pressures (fine spray and high cooling rates). Low coercivity values, less than 1 kOe, were found for the mostly amorphous magnets. Subsequent heat treatment of the latter magnets dramatically improved the magnetic properties, particularly the coercivity, up to 15.6 kOe. Energy products as high as 10 MGOe were obtained after selected heat treatments. The magnets produced by LDC were magnetically isotropic as is the case for melt‐spun ribbons and hot‐pressed magnets.

ISSN:0021-8979    

DOI:10.1063/1.344934

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A theoretical analysis of the origin of residual stresses in amorphous wires and their effect on the magnetostrictive properties has been made. The residual stress distribution (compression in the surface and tension in the center) in the wire is attributed to the different cooling rates experienced during solidification by different regions of the wire. Theoretically calculated results agree well with reported experimental data obtained from magnetic measurements.

ISSN:0021-8979    

DOI:10.1063/1.344935

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Two simple methods were introduced for measuring the magneto‐optical Kerr rotation when the light is incident upon the surface of the magneto‐optical media at zero degree angle of incidence. The methods can readily be implemented on an existing ellipsometer.

ISSN:0021-8979    

DOI:10.1063/1.344936

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The photoluminescence (pl) of copper‐related bound excitons (BE’s) in GaAs is investigated by means of resonantly excited and time‐resolved photoluminescence, as well as photoluminescence‐excitation (ple) spectroscopy. Observation of the 2sand 3stwo‐hole transitions leads to a precise value of 193 meV for the hole binding energy of the acceptor associated with theFcomplex. No evidence for such two‐hole transitions was ever detected for theCcomplex. The lifetimes of theC0and theF0BE’s are reported in addition to that of a line found at 1501.5 meV.C0BE exhibit an excited state 3.7 meV above the ground state, while no excited states were detected forF0.

ISSN:0021-8979    

DOI:10.1063/1.344937

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The conversion of the carbon‐interstitial–phosphorous‐substitutional (Ci‐Ps) pairs from configuration M4 to M1 is shown to have a strong dependence on the method of sample fabrication. This conversion can be observed only in samples that have been contaminated by boron during sample fabrication. The temperature at which the conversion to M1 occurs is closely related to the level of boron contamination. In addition, it is shown that the M1 peak is not a single defect level. M1 consists of at least two overlapping levels that have similar properties but which are clearly related to different configurations. It is proposed that the conversion of M4 to M1 involves long‐range migration of boron interstitials and that the M1 configurations involve a boron interstitial trapped at an isolated Ci‐Pspair.

ISSN:0021-8979    

DOI:10.1063/1.344938

出版商:AIP    

年代:1990

数据来源: AIP