摘要:

The dc sputtering of gold onp‐type silicon introduces sputter (damage) effects, which can be divided into surface effects and space‐charge region effects. The space‐charge region effects are investigated by capacitance profiling in combination with anodic oxide stripping of thin layers of silicon. In this way, it is possible to obtain a complete profile of sputter‐induced electrically active states, not only at the end of the space‐charge region, but up to the surface of the silicon. It is observed that donorlike states are capable of almost fully compensating the acceptor states over distances of one micrometer typically. Possible explanations for the origin of these states in terms of field‐enhanced diffusion of species activated during the sputter process are discussed.

ISSN:0021-8979    

DOI:10.1063/1.334398

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

p‐type metal‐oxide‐semiconductor (MOS) capacitors with various oxide thickness (less than 200 A˚) are stressed by Fowler–Nordheim (F–N) tunneling constant current with negative gate bias, and high frequency and low frequency capacitance‐voltage (C‐V) characteristics have been used to investigate the charge trapping phenomenon in thermally grown thin SiO2films. Under constant current stress, high frequencyC‐Vcurve shifts negatively, and flatband votage shifts &Dgr;VFBdon’t saturate even at large injected chargeF. In order to explain this behavior, we propose the expression, &Dgr;VFB=A[1− exp(−&sgr;F)]+KF. The first term indicates hole trapping by the preexisting traps and the second term means the generation factor due to traps generated under stress. A fitting parameterAis nearly in proportion to the square of SiO2thickness. This can be interpreted with the uniform distribution of bulk hole traps throughout the SiO2. Both capture cross section &sgr; and generation factorKrapidly decrease with decreasing SiO2thickness. From the results of low frequencyC‐Vcharacteristics, the interface states with very high density of the order of 1013/cm2 eV are generated over a wide range of band gap.

ISSN:0021-8979    

DOI:10.1063/1.334399

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

For performing electron‐beam‐induced current (EBIC) measurements on sufficiently large samples, the use of a ‘‘planar‐collector geometry’’ (i.e., with the collector covering part of the irradiated surface itself) is very attractive. However, the pertinent theoretical EBIC curves for finite surface‐recombination velocitiesshave so far been lacking. This paper presents the complete theoretical expressions for arbitrary values ofsand diffusion lengthL. Simple asymptotic solutions are given for point‐ and finite‐size generation sources. Easy methods are developed to facilitate the application of these solutions in the practical evaluation ofLandsfrom experimental EBIC curves. These methods are applied to experimental data available through the literature.

ISSN:0021-8979    

DOI:10.1063/1.334400

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Dopant profiles of low‐dose channel implant in silicon‐on‐sapphire (SOS) field‐effect transistors are investigated by comparing results from various techniques, including theoretical calculation by the Stanford University integrated‐circuit process simulation program (suprem) and experimental measurements by secondary ion mass spectrometry (SIMS), capacitance‐voltage (C‐V), spreading resistance and metal‐oxide‐semiconductor Hall effect. It is shown that, for both phosphorus‐ and boron‐implanted SOS films having constant doping profile at a level close to 1×1016cm−3, as predicted bysupremand measured by SIMS, the charge density measured byC‐Vtechnique and free carrier concentration obtained from spreading resistance technique decrease with increasing distance from the Si surface. For SOS films implanted to a level greater than 1× 1017cm−3boron, the dopant profile obtained by SIMS analysis coincides with the charge density profile, measured byC‐Vtechnique, and the free carrier concentration profile, deduced from spreading resistance, and the actual mobility in SOS films.

ISSN:0021-8979    

DOI:10.1063/1.334401

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Noise properties of Josephson harmonic mixers were investigated both by simulation studies and by experiments. It was clarified that the unbiased mixing operation peculiar to even‐harmonic Josephson mixers has a lower noise temperature than the biased operation. A minimum noise temperature of 121 K was obained for an unbiased second‐harmonic Josephson mixer at 70 GHz. The cause of this low‐noise property of the unbiased mixing was attributed mainly to the nonexistence of noise down‐conversions by the odd‐harmonics of LO and the Josephson oscillation.

ISSN:0021-8979    

DOI:10.1063/1.334402

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Preparation and characteristics of refractory Nb/Al‐oxide‐Nb Josephson tunnel junctions with critical current densitiesjcfrom ∼103to ∼4×104A/cm2were studied with respect to junction quality, uniformity, reproducibility andjccontrol. The key steps leading to improved junction parameters are emphasized and compared with previously used procedures. The results includejmaxc/jmincof 1.2, on a 1‐in. chip,Vmup to 56 mV in junctions withjc∼103A/cm2, andVmup to 24 mV withjc∼6×103A/cm2. Good run‐to‐run reproducibility and control ofjcare also demonstrated. In particular,jcis shown to increase by a factor of ∼40 when the oxygen pressure during thein‐situoxidation of the Al overlayer is reduced from 1 to 0.01 Torr.

ISSN:0021-8979    

DOI:10.1063/1.334403

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The basic physical mechanism responsible for the general behavior of eddy current losses versus magnetizing frequencyfmis recognized in the competition between the external field and local internal fields, due to magnetostatic, coercive, and eddy current effects. The concept of magnetic object, corresponding to a group of neighboring walls evolving in a highly correlated fashion, is introduced in order to take into proper account the role of short‐range internal correlation fields. With a random spatial distribution of magnetic objects, the dynamic loss is essentially a function of the numbern˜ of magnetic objects which are simultaneously active at each value offm. It is shown that the dynamic balance between applied field and local eddy current counterfields leads, with increasingfm, to a progressive increase ofn˜ governed by the simple linear lawn˜=n˜0+Hexc/V0, whereHexcrepresents the part of the applied field in excess of the hysteresis and classical contributions. Under these conditions, a general law of losses is derived, which turns out to be in excellent agreement with several experimental results concerning different iron‐based ferromagnetic alloys. On the basis of the general validity of the obtained loss equation, a bidimensional map of dynamic losses is defined and constructed, in which the parametersn˜0andV0are used as orthogonal coordinates of representative points characterizing the loss behavior of different materials. This map provides the proper basis for a general classification of dynamic losses, which might also be useful from the applicative point of view.

ISSN:0021-8979    

DOI:10.1063/1.334404

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

In the preceding paper [J. Appl. Phys.57, 2110 (1985)], it was shown that the behavior of eddy current losses in ferromagnetic materials can be fully characterized, in general, in terms of two parameters, the effective numbern˜0of active magnetic objects present at low magnetizing frequencyfm, and the fieldV0, determining the ability of the external field to increase the number of active objects with increasingfm. In this paper, the connection ofn˜0,V0with several microstructural and magnetic properties of iron‐based ferromagnetic alloys is investigated. It is shown that, in agreement with theoretical predictions,n˜0is, in general, weakly dependent on other physical properties, attaining values ∼1 in most cases. Only the application of a tensile stress leads to a drastic increase ofn˜0above this limit.V0, on the contrary, turns out to be very sensitive to the type of material. It continuously decreases with decreasing degree of magnetic orientation, changing by about two orders of magnitude when we pass from monocrystalline to nonoriented SiFe alloys. By mapping dynamic losses in the plane (V0,n˜0), it is shown that the loss behavior in the frequency range of applicative interest (fm∼50 Hz) is essentially governed byV0only, whilen˜0does not play any significant role. The attempt to work out a unified interpretation of the observed properties ofV0leads to a most unexpected direct connection between hysteresis and dynamic losses, which probably underlies some general physical principle, governing the global features of the magnetization dynamics far beyond the details of specific situations.

ISSN:0021-8979    

DOI:10.1063/1.334405

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Polarized neutron scattering with polarization analysis on single crystals may allow one to remove some ambiguities in the determination of a magnetic structure, especially for high symmetry systems. The direction of the Fourier components of the magnetic moments and the relative population of different associated magnetic domains are, in particular, obtained. Application is made on a cubic antiferromagnetic rare‐earth compound, PrAg. Among the different possibilities, it is proposed that this compound orders in a double‐Q(biaxis) magnetic structure with local moments lying along twofold directions.

ISSN:0021-8979    

DOI:10.1063/1.335467

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The magnetoacoustic resonance between phonons and magnons is studied analytically on the basis of a set of linearized magnetoelastic equations, which was previously deduced from a rotationally invariant nonlinear theory for uniaxial antiferromagnets of the easy‐axis type. More specifically, the present paper investigates the less studied case where the bias magnetic field is either ‘‘moderate’’ or strong relative to some material parameter. Various types of dispersion and magnetoacoustic resonance couplings are exhibited depending on whether waves propagate along the direction of or orthogonal to the symmetry axis. In some cases a fast transverse elastic mode couples with both upper and lower magnon branches, while longitudinal and slow transverse elastic modes travel independently. In another case both fast and slow transverse elastic modes couple with both upper and lower magnon branches. In the case that most closely resembles the case of ferromagnets, left‐circularly polarized transverse phonons and magnons couple at both high and low magnetoacoustic resonance points, while the right‐circularly polarized transverse phonons are only rendered slightly dispersive for small wave numbers. These coupled dispersion behaviors are studied analytically (asymptotics) in terms of a small parameter which represents globally magnetoelastic couplings. This paper concludes the study of magnetoacoustic resonance in antiferromagnetic insulators which was started in a previous paper concerned with the case of weak bias magnetic fields.

ISSN:0021-8979    

DOI:10.1063/1.334352

出版商:AIP    

年代:1985

数据来源: AIP