摘要:

The effects of the implantation dose and annealing on magnetization (4&pgr;Ms), lattice constant strain (&Dgr;d/d), and change in the anisotropy field (&Dgr;HK) of a layer implanted with Ne+or H+ions in bubble garnet films have been investigated using a vibrating sample magnetometer (VSM), the double crystal x‐ray technique, and ferromagnetic resonance measurements. The magnetic and crystalline properties of Ne+or H+ion‐implanted layers were quite different. Saturation magnetization of the H+ion‐implanted layer decreased gradually with &Dgr;d/dbeyond 1%, while that of the Ne+ion‐implanted layer decreased abruptly above 1%. &Dgr;HKof the Ne+ion‐implanted layer was proportional to &Dgr;d/dup to a saturation point of about 1%; however, &Dgr;HKof the H+ion‐implanted layer continued to increase after &Dgr;d/dpassed 1%. The other distinct difference between the H+and Ne+ion‐implanted specimens was the temperature necessary to obtain annealing effects. In the H+ion‐implanted layer, annealing in the lower (around 200 °C) temperature range had a relatively larger effect on 4&pgr;Msand &Dgr;HKthan with the Ne+ion‐implanted layer.

ISSN:0021-8979    

DOI:10.1063/1.331112

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Polarization modulation ellipsometry has been used to determine the optical constants of Si for photon energies from 1.64 to 4.73 eV (755 to 262 nm) at 300 as well as 10 K. The results were interpreted using a 2‐boundary, 3‐layer model (air‐SiO2‐Si); the inclusion of an interface layer between the SiO2and Si did not greatly affect the derived optical constants below ∼3.5 eV. The accuracy of the results has been carefully evaluated, the error in the index of refraction (n) being < 1%, while the error in the extinction coefficient (k) or the absorption coefficient (&agr;) being dependent upon the magnitude, ∼15% at &agr; = 104cm−1, ∼6% at &agr; = 105cm−1, and ∼1.5% at &agr; = 106cm−1. The room temperature absorption coefficient results represent the best spectroscopically available values from ∼2.5 to ∼3.5 eV (∼350 to 500 nm), while results at 10 K represent the best values available over the entire wavelength region measured. A comparison with previously published data is presented.

ISSN:0021-8979    

DOI:10.1063/1.331113

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The results obtained by photothermal ionization spectroscopy on acceptors in high‐purity germanium are presented. The distribution of the residual acceptor impurities, boron and aluminum, in high‐purity germanium crystals are studied by lightly doping the crystals with gallium, and using semiconductor statistics to determine the relative concentrations of the shallow acceptors from their relative peak heights in the spectra. Under the conditions of growth (SiO2crucible, H2(g) ambient) the distributions of aluminum and boron do not follow the equation for normal segregation The distribution profiles of aluminum indicate that it is being removed from the melt during growth while the distribution profiles of boron are usually consistent with boron being added to the melt during growth. Data were taken with a high resolution (0.10 cm−1) Fourier transform spectrometer. Transition energies are tabulated for the acceptors observed. Three new shallow acceptors are reported. Two haveDtransitions at 60.20 and 64.69 cm−1, respectively. The other acceptor has a split ground state withDtransitions at 69.12 and 73.77 cm−1. The deepest acceptor observed was neutral copper with a binding energy measured to be 348.9 cm−1(43.27 meV).

ISSN:0021-8979    

DOI:10.1063/1.331114

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Time resolved photoluminescence experiments show the importance of photon recycling inp‐(Ga,Al)As:Si liquid‐phase epitaxial layers with a graded band gap. In particular, it is confirmed that the drift of the electrons in the built‐in electric field may be neglected. Strong inhomogeneities of the electron lifetime are experimentally demonstrated and explained by the varying compensation of the amphoteric Si doping. The large contribution of photon recycling to the externally observed spectra is shown by ’’front’’ and ’’back’’ excitation of the cw photoluminescence. The internal quantum efficiency at room temperature is probably appreciably above 20%.

ISSN:0021-8979    

DOI:10.1063/1.331115

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Electroluminescence diodes have been prepared from laser‐irradiated (Al,Ga)As‐heterostructures where one of the layers forming thep‐njunction is Ge doped. The diodes exhibit a new luminescence band shifted to lower energies by 160 meV with respect to the band‐to‐band recombination. At low current densities the observed edge emission intensity within the new band is more than quadrupled as compared to the band‐to‐band recombination. At current densities above 2.0 kA/cm2the band‐to‐band recombination dominates. The measured carrier lifetimes for the new band and the band‐to‐band transition are 15 and 9 ns, respectively.

ISSN:0021-8979    

DOI:10.1063/1.331116

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The excitation spectra of the 1.2‐ and 2.0‐eV emissions in Cd1−xMnxTe were measured using a dye laser, and various lines from an Argon ion laser. Both emissions have their excitation thresholds near the Mn2+ 6A1(6S)→4T1(4G) absorption edge. Forx∼0.7, the excitation spectra at higher energies are similar for both emissions and are related to the Mn2+ 6A1(6S)→4T2(4G) transition. For allxin this range, there is a drop of intensity above the Mn2+absorption edge, ascribed here to competitive intrinsic absorption, which does not lead to Mn2+emission. Details of these behaviors are reproduced by a model which assumes separate Urbach tails for the Mn2+and intrinsic absorptions.

ISSN:0021-8979    

DOI:10.1063/1.331117

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Various bilayer structures consisting of metal and silicon were investigated as possible candidates for the optical recording medium. The silicon‐on‐metal bilayers offer tunability with a reasonable thickness of Si in the visible spectrum with a typical reflectivity less than 5%. Of the two possible writing processes, the low‐power process of silicide formation has a threshold power of 30 mW for a Rh‐Si bilayer which provides a reflectivity change in excess of 40%. The absence of raised rims around the written spots offers a smooth morphology that is compatible with encapsulation.

ISSN:0021-8979    

DOI:10.1063/1.331118

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Normalized ionization probabilities &agr;+are reported for binary Fe‐Ni alloys under O+2bombardment at a 45° incidence angle. It is shown that the dependence of &agr;+on the composition is much smaller than at normal incidence. Photoemission spectroscopy reveals that both nickel and iron remain essentially metallic under oblique‐incidence bombardment, whereas almost complete oxidation occurs at normal incidence. This is attributed to our observation that sputter yields under oxygen bombardment increase much faster than cos &agr;−1.

ISSN:0021-8979    

DOI:10.1063/1.331119

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Particles suspended in a gas may emit photoelectrons upon irradiation with ultraviolet light. It is shown that photoemission from small particles involves material and surface dependent physical processes that yield new information, especially on ultrafine particles not accessible to the well‐known diffusion charging. An apparatus is presented for the measurement of the electric mobility and the charge generated on particles in the atmosphere using a monochromatic low‐pressure Hg arc. Particles generated by combustion of organic material, e.g., auto exhaust, are charged with high efficiency. This offers a new way to detect and/or remove such particles from the air. In outside air the concentration of photoelectrically active particles has a diurnal cycle which also depends on the meteorological conditions. Surprisingly, highly mobile particles are detectable even during rainfall.

ISSN:0021-8979    

DOI:10.1063/1.331120

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Conductivity of a doubly‐oriented polymer along the arbitrary direction (X,Y,Z) is presented as a function of the principal values of the conductivity &sgr;x, &sgr;y, &sgr;zof the orientation units (’’crystals’’) and a double orientation function of ’’crystals’’. Principal values of the electrical conductivity in doubly‐oriented nylon 12 films were measured and &sgr;x, &sgr;y, &sgr;zof the crystals of nylon 12 were estimated assuming a suitable distribution of crystals in nylon 12 film. It is observed that &sgr;xis much larger than &sgr;yand &sgr;z. Thexdirection was defined as the direction of the chain of the hydrogen bonds, i.e., the conductivity along the direction of hydrogen bonds is the largest. The average conductivity &sgr;0(3&sgr;0= &sgr;x+&sgr;y+&sgr;z), which should be independent of the results of orientation, decreased as the roll ratio became large. The decrease of &sgr;0shows the change of the conduction properties of crystals by rolling, and is considered as a result of the change of the microstructure of nylon 12.

ISSN:0021-8979    

DOI:10.1063/1.331121

出版商:AIP    

年代:1982

数据来源: AIP