摘要:

The infrared absorption of a multiple quantum‐well structure with coupled wells is studied experimentally. The structure consists of 40 repeats of two coupled quantum wells with a wider doped GaAs well and a narrower undoped GaAs well and AlAs barriers. A strong absorption due to an intersubband transition in the wider wells is seen at about 0.14 eV, which shifts in transition energy when a negative bias is applied and decreases in absorption strength when a positive bias is applied. The shift is due to many‐body effects on the transition energy when the electron density in the wider well is reduced, and the decrease is attributed to the blocking of the final state when the upper state in the wider well is populated.

ISSN:0021-8979    

DOI:10.1063/1.346304

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We propose a theoretical interpretation of the unusual magnetic properties of ultrasoft magnetic films. Effective‐medium theory is shown to reproduce remarkably well the dependence of the low‐frequency susceptibility with magnetic field. In order to understand the dynamical susceptibility, one needs to generalize the usual Landau–Lifshitz equation and introduce an anisotropic dissipative term. The two relaxation coefficients &agr;1,&agr;2are determined by a fit of the experimental data. &agr;2is found to be large, perhaps reflecting the strong inhomogeneity of the local anisotropy field.

ISSN:0021-8979    

DOI:10.1063/1.346305

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The room‐temperature cathodoluminescence of diamondlike films produced by glow discharge is reported. The material was deposited onto dc biased substrates maintained at relatively low temperature (<100 °C). Two visible peaks around 2.3 eV (green) and 2.7 eV (blue‐violet) were identified which are commonly found in natural and synthetic diamond, indicating the presence of crystalline particles in the films. Moreover, x‐ray diffraction spectra of the samples before cathodoluminescence studies are identical to the ones reported for natural powder diamond.

ISSN:0021-8979    

DOI:10.1063/1.346306

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Low‐temperature photoluminescence and photoluminescence excitation experiments have been performed on lattice‐matched InGaAs/InP quantum wells, wires, and dots grown by metalorganic vapor‐phase epitaxy and processed by electron‐beam lithography. An enhancement of the intrinsic photoluminescence mechanism is found with decreasing dimensionality.

ISSN:0021-8979    

DOI:10.1063/1.346307

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

High‐dose Co ion implantation in Si at elevated temperatures is used to synthesize buried CoSi2layers. It is shown that inclusions of CoSi occur in the CoSi2layer, when the stoichiometry level is exceeded at the peak of the Co distribution. These CoSi precipitates are observed prior to annealing and after a 5 s rapid thermal annealing (RTA) at 800 °C. During furnace annealing at 1000 °C or for RTA at temperatures above 900 °C, the CoSi phase transforms into CoSi2. In this communication the results of a transmission electron microscopy study of the CoSi inclusions are correlated with the Co depth profile, as determined by Rutherford backscattering spectrometry.

ISSN:0021-8979    

DOI:10.1063/1.346308

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We analyzed the Raman spectra and x‐ray diffraction of two GaAs/Al0.3Ga0.7As superlattices grown by molecular‐beam epitaxy on a 4 ° misoriented (001) GaAs substrate and an exactly (001)‐oriented GaAs substrate respectively. From the frequency shifts of the longitudinal‐optical‐ (LO) confined phonons in the Raman spectra and the variation in linewidths of both the LO‐confined phonons and the satellite peaks in x‐ray diffraction, we found that the 4 ° misorientation of the GaAs substrate from (001) toward [110] direction improves the interface quality of the superlattices.

ISSN:0021-8979    

DOI:10.1063/1.346283

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.347206

出版商:AIP    

年代:1990

数据来源: AIP

ISSN:0021-8979    

DOI:10.1063/1.347205

出版商:AIP    

年代:1990

数据来源: AIP