摘要:

Magnetic properties and read‐write characteristics of Co‐Ni‐P plated disks are examined. In‐plane coercive force and squareness increase with increasing the thickness of an Ni‐P layer which is formed between the substrate layer (Cu‐Sn) and Co‐Ni‐P film. However, media noise increases with thickening of the Ni‐P layer. The relationships between magnetic properties and media noise are investigated by measuring rotational hysteresis (Wr) and its integral (RH). As a result, it is found that media noise closely correlatesRHvalues: smallerRHvalues cause less media noise. This result shows that media noise is dominated by the magnetization process, and magnetic thin film in which the magnetization process occurs through coherent rotation is desirable for magnetic recording media.

ISSN:0021-8979    

DOI:10.1063/1.341421

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The effect of uniaxial mechanical stress on the Hall coefficient ofn‐type silicon has been measured for various crystallographic orientations, and piezo‐Hall coefficientsP12andP11‐P44have been derived for electron concentrationsnbetween 1014and 1016cm−3and temperatures ranging from −80 to +100 °C. In this range the piezo‐Hall effect is found to be as important as the piezoresistance effect which is understood in terms of the many‐valley band structure of silicon with anisotropic energy minima. For Hall plates in the (100) and the (110) plane of silicon the resulting longitudinal and transverse piezo‐Hall coefficients at room temperature are plotted as a function of their orientation in the plane. It turns out that the piezo‐Hall as well as the piezoresistance effects are minimized for a Hall plate in the (110) plane with the current flow roughly parallel to ⟨11¯1⟩.

ISSN:0021-8979    

DOI:10.1063/1.341422

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Infrared photoluminescence measurements have been made of a number of HgTe‐CdTe superlattice samples as a function of temperature from liquid He to room temperature. The experimental results are compared with calculations of the band gap of these materials and the effects of layer thicknesses, valence‐band offset, effective mass, and Hg in the CdTe layers are investigated. The data are in reasonable agreement with the calculations for zero (or small) valence‐band offset and no Hg in the CdTe layers.

ISSN:0021-8979    

DOI:10.1063/1.341423

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The ablation of polymethylmethacrylate (PMMA) at both 248 and 193 nm has been studied using photoacoustic techniques. The acoustic responses of PMMA during the ablation process are resolved into a bipolar, thermal component, and a unipolar, ablative component. This latter component is correlated to the center‐of‐mass velocity of the ablated material. Fluence‐dependent studies show that the fragment center‐of‐mass velocity increases with increasing fluence even after the etch rate has reached saturation. In addition, results are presented suggesting that an increase in the absorption of the laser radiation by the fragments occurs at fluences above ∼4 J/cm2causing a change in the profile of the ablated area.

ISSN:0021-8979    

DOI:10.1063/1.341424

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Measurements of the electroreflectance (ER) of smooth and microstructured Ag surfaces have been performed with use of Al‐Al2O3‐Ag tunnel junctions at room temperature. The ER spectra of smooth silver are found to be in excellent agreement with those reported earlier by Kolb and Kotz [Surf. Sci.24, 417 (1971)] in electrochemical cells. A dip ath&ngr;=3.78 eV can be seen forppolarization and a peak appears ath&ngr;=2.94 eV due to the surface plasmon excited at the Al‐Al2O3interface. In the microstructured junctions the very high field (∼1010V/cm) present at the top of the Ag posts induces a shift of the maximum at 3.9 eV forppolarization and a large negative signal in the 3–4 eV range which cannot be observed in the conventional ER experiments. The free‐electronlike theory of the ERs does not account for these experimental data.

ISSN:0021-8979    

DOI:10.1063/1.341425

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Detailed measurements of polarization‐dependent gain‐current characteristics have been carried out on (111)‐ and (100)‐oriented GaAs/AlGaAs single‐quantum‐well lasers by using Hakki and Paoli’s method. Polarization‐dependent gain‐current characteristics have been found to strongly depend on the well width and the quantization direction. The saturation of gain with the injection current and the width of the gain spectrum depends on the well width, and they are also affected by the transition between the higher‐order subbands. Experimental results of polarization‐dependent spontaneous emission are also presented. The simple selection rule and the effective‐mass theories do not quantitatively account for the experimental results.

ISSN:0021-8979    

DOI:10.1063/1.341426

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A novel absorption technique, calorimetric absorption spectroscopy (CAS), is described and modeled in detail. The technique is more sensitive than any other low‐temperature absorption technique reported hitherto and it is quantitative. Quantum efficiencies can be determined by combining CAS with calorimetric transmission spectroscopy. The method is based on integral detection of phonons emitted during nonradiative recombination processes. A low‐temperature carbon resistor acts as phonon detector. The sensitivity of CAS is so large that a simple combination of a tungsten lamp and a spectrometer can be used as the illumination source. Depending on the excitation density, &agr;dproducts down to 10−8can be detected. These features make it possible to apply CAS for the characterization of the interface structure of single quantum wells with thicknesses of less than 1 nm as well as for the study of the fine structure of deep traps in semiconductors. Examples for all these applications are given.

ISSN:0021-8979    

DOI:10.1063/1.341427

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Reflectivity spectra in the reststrahlen region (100–250 cm−1) are presented for bulk zinc blende Cd1−xMnxTe crystals at 2, 50, and 300 K and forx=0 to 0.64, covering nearly the entire possible composition range for cubic structure. Kramers‐Kronig analysis gives the transverse and longitudinal phonon frequencies. The Lorentz model confirms these results and also gives mode strengths and damping constants. Compositional dependence of the phonon energies is predicted by the random element isodisplacement model.

ISSN:0021-8979    

DOI:10.1063/1.341428

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Sputtering of Si in a Cl2environment by Ar+and Xe+ions with energies down to 75 eV has been investigated. Mass spectra and time‐of‐flight distributions of the sputtered species have been measured. Under 75‐eV Ar+‐ion bombardment of the Si target, SiCl, SiCl2, SiCl3, and/or SiCl4are sputtered. When increasing the ion energy the SiCl4contribution decreases in comparison with SiCl. This is caused by the fact that the newly formed Si‐Cl compounds are sputtered at a high rate compared to the rate of SiCl4formation. Time‐of‐flight distributions indicate that under 100‐eV Ar+‐ion bombardment the species are not sputtered by a collision‐cascade mechanism. The spectra can be fitted by Maxwell–Boltzmann distributions at a high (>2000 K) temperature. Increasing the Ar+‐ion energy to approximately 250 eV the time‐of‐flight spectra of the sputtered species change from Maxwell–Boltzmann‐like into spectra as expected for a collision‐cascade mechanism. For low‐energy Xe+ion bombardment the sputtered species also show Maxwell–Boltzmann time‐of‐flight distributions. The change from Maxwell–Boltzmann to collision‐cascade distributions occurs at higher ion energies than for Ar+‐ion bombardment. The results obtained for low ion energies are discussed in terms of evaporation from an ion‐induced hot spot.

ISSN:0021-8979    

DOI:10.1063/1.341429

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

A simplified viscoelastic analysis has been made of the stress evolution during two‐dimensional (2D) oxidation of silicon substrates, with the objective of learning the effect of process parameters such as temperature and steam pressure. A cylindrical silicon surface was chosen for simplicity of analysis, and yet it still has most of the essential elements pertinent to practical problems such as, e.g., the oxidation of trench corners in silicon integrated circuits. With correlations between the viscosity and the hydroxyl content of SiO2, and between the hydroxyl content and the steam pressure, the analysis shows that stress reduction can be achieved by carrying out oxidation at high steam pressures. However, stresses remain rather high if the oxidation temperature is as low as 800 °C. For a linear‐parabolic oxidation kinetics, both the oxide and the substrate stresses do not increase indefinitely with the increase of oxide thickness, but reach their respective peaks at oxide thicknesses that are dependent on process parameters. The present results should be useful in serving as guidelines in the selection of 2D oxidation conditions. The accuracy of a previous 2D oxidation model based on the viscous flow of an incompressible fluid has also been assessed with reference to the viscoelastic model. The incompressible‐fluid model is found to be quite accurate at high temperatures ≳900 °C.

ISSN:0021-8979    

DOI:10.1063/1.341430

出版商:AIP    

年代:1988

数据来源: AIP