摘要:

We have found by resistivity measurements and deep‐level transient spectroscopy that four kinds of oxygen‐related shallow donors, OD1–OD4, successively appear around 500 °C in the time region 10–106min and carbon greatly affects their generation behavior in Czochralski silicon. The formation of OD2 and OD3 donors was enhanced by the presence of carbon, while that of OD1 and OD4 donors was retarded. The OD1 donor is identified as the so‐called thermal donor that consists of several kinds of double donors observed so far by infrared studies. The OD2 donor is a new kind of donor discovered recently by us. OD3 and OD4 donors, which were formed by very prolonged annealing around 500 °C, are suggested to have correlations with so‐called new donors normally generated above 600 °C. The origins of these oxygen‐related donors are discussed in relation to oxygen precipitation.

ISSN:0021-8979    

DOI:10.1063/1.346585

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A new superlattice system suitable for infrared detection in the 8–12 &mgr;m wavelength range is proposed. The system is a sawtooth doping superlattice (SDS) constructed by alternatingn‐ andp‐type &dgr;‐doped layers in the narrow gap III‐V alloy InAs1−xSbx(x≊0.6). The electronic structure of such materials is examined theoretically using a multiband envelope function formalism. The results indicate that, with relatively modest doping levels (<4×1012cm−2) and short periods (<300 A˚), an InAs0.4Sb0.6SDS exhibiting significant optical absorption out to 12 &mgr;m at 77 K should be possible.

ISSN:0021-8979    

DOI:10.1063/1.346586

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The process of shock wave generation and shock evolution in a solid target by confined laser plasma, in the range 108–1010W/cm2incident intensity, is analyzed with the use of computer simulations. Predicted variations of plasma pressure are consistent with theoretical results from simple analytical models and with experimental data. The simulations also provide a complete description of various effects such as target or confinement thickness and acceleration of thin foils.

ISSN:0021-8979    

DOI:10.1063/1.346587

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We propose two semiempirical expressions for representing condensed‐phase heat capacities over a wide temperature range. Both can be integrated analytically to give closed‐form expressions for entropies and enthalpies. As examples, we use the expressions to represent the molar heat capacities, entropies, and enthalpies of ⟨Si⟩ and ⟨Al⟩.

ISSN:0021-8979    

DOI:10.1063/1.346588

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

This communication presents a study of the dispersion relation for propagation in axisymmetric transverse magnetic modes along a dielectric‐coated conducting cylinder embedded in a strongly magnetized plasma, the cylinder axis being placed parallel to the static magnetic field. Dispersion characteristics, covering all possible values of the plasma frequency, are plotted for typical values of &egr;danda/b, where &egr;dis the dielectric constant of the coating, andaandbare the radii of the cylinder without and with the coating, respectively. A discussion of how the characteristics would change if &egr;dora/bis varied is also presented. In particular, the special case in which &egr;d=1 and the coating is replaced by a vacuum sheath is investigated in detail.

ISSN:0021-8979    

DOI:10.1063/1.346589

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The changes in the bound‐state energies and oscillator strength for intersubband transitions brought about by a thin barrier in the middle of an asymmetric quantum well are calculated, with a particularly close look at such changes as the middle barrier height approaches the bound‐state energies. It is found that the oscillator strength goes through a slight change as the barrier height approaches the ground‐state energy but an abrupt change when it approaches the excited bound‐state energy. A suitable explanation for this change is provided. A similar tailoring of the intersubband transitions is also achieved by placing a delta‐function potential in the vicinity of the middle of the well but without any abrupt change in the oscillator strength.

ISSN:0021-8979    

DOI:10.1063/1.346590

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Surface acoustic wave (SAW) technique is used to investigate the electrical and optical properties of Fe‐doped InP. Transverse acoustoelectric voltages (TAV) versus incident photon energy and applied bias voltage are measured to change the surface conductivity induced by impurity level trapping of the carriers. After the sample is etched, an impurity level is detected around 1.405 eV which considerably changes the shape of the experimental TAV versus incident photon energy and TAV versus bias voltage measurements. SAW semiconductor interaction models that tentatively explain the observed data are discussed.

ISSN:0021-8979    

DOI:10.1063/1.346591

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Manganite (Mn1.5Co1Ni0.5O4) based thermistors in bulk form are well known. We have earlier reported that the electronic properties [sheet resistivityRsand temperature coefficient of resistance (TCR)] of Ag‐loaded, manganite‐based thick‐film thermistor pastes show a sudden reduction in sheet resistivity (from M&OHgr;/sq to &OHgr;/sq) and a reversal of TCR [from negative temperature coefficient (NTC) to positive temperature coefficient (PTC)], above a critical percentage of Ag loading (50% by weight) and that this behavior follows a modified percolation theory. Here the above pastes are characterized by x‐ray diffraction analysis. Our x‐ray diffraction results do indicate the formation of a Ag complex upon Ag loading (30%–60% by weight) as postulated in the earlier paper. However, the system seems to be still more complex, as the channel formation required for percolation theory may not be of a single material but of two materials, i.e., Ag and an Ag complex.

ISSN:0021-8979    

DOI:10.1063/1.346592

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.347200

出版商:AIP    

年代:1990

数据来源: AIP