摘要:

We report the first observation of resonant self‐pumped phase conjugation at diode laser wavelengths. A phase conjugate reflectivity of 0.01%, and a cw threshold intensity of 75 W/cm2were measured.

ISSN:0003-6951    

DOI:10.1063/1.104933

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The structure of a vicinal Si(111) stepped surface is analyzed by force microscopy in air to reveal a fine structure in a step bunching area, and a monoatomic step in a terrace region. Step heights of one to three monoatomic layers were also observed on a debunched Si(111) surface. These steps have low crystallographic indices [112¯], [101¯], [01¯1], [213¯], and [ 1¯2¯3]. The force microscope images were in good agreement with scanning electron microscope and reflection electron microscope images observed in ultrahigh vacuum just after sample annealing by resistive heating.

ISSN:0003-6951    

DOI:10.1063/1.104934

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Polycrystalline boron nitride films have been deposited using microwave plasma‐enhanced chemical vapor deposition. IR absorption spectra of films deposited using NaBH4as the boron source in NH3and H2gases showed absorptions which are nearly the same as the characteristic vibrational modes seen in cubic and pyrolytic boron nitrides. Films deposited at 5 Torr also showed electron diffraction patterns for pyrolytic boron nitride, turbostratic boron nitride and cubic boron nitride. At higher gas pressures, only rings consistent with the formation of amorphous and cubic boron nitride were observed. Although the Raman spectra from a film deposited at 60 Torr showed broad peaks at ∼1080 and ∼1310 cm−1, the positions of the Raman lines for cubic boron nitride, no x‐ray diffraction lines could be observed except that of the silicon substrate.

ISSN:0003-6951    

DOI:10.1063/1.105236

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We demonstrate experimentally that the far‐infrared photoresponse of GaAs/AlGaAs heterostructures at photon energies corresponding to cyclotron resonance absorption is strongly enhanced in the adiabatic transport regime of the quantum Hall effect (QHE). Ideal adiabatic transport is characterized within the edge channel picture of the QHE by the absence of interedge channel scattering. We realize adiabatic transport by the means of a multiple gate finger structure, which is used for a selective population of the edge channels. The cyclotron resonance absorption is interpreted as an additional interchannel scattering process increasing the magnetoresistance.

ISSN:0003-6951    

DOI:10.1063/1.104935

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We propose and demonstrate a novel concept for intersubband detectors at operating wavelengths of 3–5 &mgr;m using GaAs quantum wells. An extremely large intersubband spacing is obtained by using ultrathin AlAs barriers on either side of the GaAs quantum wells followed by a thicker Al0.3Ga0.7As layer. Simultaneously, the confining AlAs layers act as tunnel barriers which allow an electrical detection of the intersubband excitation.

ISSN:0003-6951    

DOI:10.1063/1.104936

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Optically detected microwave‐induced impact ionization of excitons and shallow donors is studied in Yb‐doped InP grown by metalorganic chemical vapor deposition. The experimental results directly confirm that Yb3+intrashell emission is induced by nonradiative recombination of Yb bound excitons due to an impurity Auger effect. Yb3+ions in InP are found to bind excitons with the electron being localized first, followed by subsequent hole capture.

ISSN:0003-6951    

DOI:10.1063/1.104937

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Low‐temperature precipitation of neutral interstitial iron inn‐type silicon is investigated by means of photocapacitance measurements. Isothermal kinetics as well as iron depth profiles are observed which agree very well with an outdiffusion mechanism of iron to the sample surface. From these data the diffusion coefficient of neutral iron in silicon could be determined. Comparison with published results on positively charged iron inp‐type silicon reveals a higher stability of neutral iron as well as a charge state dependence of its diffusion mechanism.

ISSN:0003-6951    

DOI:10.1063/1.104938

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

The effect of annealing one monolayer of Sb onp‐InP on the surface Fermi level position and the band bending due to Ag deposition on these well‐ordered surfaces have been studied using photoemission spectroscopy. The adsorption of one monolayer of Sb onp‐InP gives a Fermi level position 0.85 eV above the valence band maximum (VBM). However, with increasing annealing temperature, the band bending decreases and recovers to nearly the flatband condition above 200 °C. The Fermi level movement of annealed InP shows a correlation with the surface stoichiometry of phosphorus and indium. Ag deposition on these annealed Sb/p‐InP interfaces gives an anomalously low band bending of 0.5 eV above the VBM.

ISSN:0003-6951    

DOI:10.1063/1.104939

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

We examined high‐resolution diffraction profiles of as‐grown and annealed magnetic‐field‐applied Czochralski (MCZ) silicon crystals which were about 300 &mgr;m thick and [001] oriented, and compared these profiles with the ultraplane wave x‐ray topographs. Rocking curves for the symmetric 220 diffraction were measured in the Laue geometry using a (+m, −n, +n) separated three‐crystal monochromator. Strain introduced in the sample preparation process gave a reduced oscillatory profile of a rocking curve although chemical etching recovered subsidiary peaks of the rocking curve. Strain frozen in as‐grown crystals also gave a reduced oscillatory‐profile, but a large number of oxygen precipitates produced by thermal annealing caused little reduction of subsidiary peaks.

ISSN:0003-6951    

DOI:10.1063/1.104940

出版商:AIP    

年代:1991

数据来源: AIP

摘要:

Three different ways of forming oxide overlayers on GaAs(110) have been examined with x‐ray photoemission. First, Cr atoms were deposited onto cleaved GaAs(110) at 300 K, producing a disrupted region over which Cr metal grew. Subsequent exposure to O2resulted in an inhomogeneous overlayer with areas of thick Cr2O3‐like oxides in addition to As and Ga oxides. GaAs oxidation was enhanced by Cr‐induced surface disruption, but there was no evidence of a catalytic process. Second, metallic clusters of Cr containing hundreds of atoms were condensed onto GaAs(110). In this case, no substrate disruption was observed at low temperature. O2exposure resulted in Cr2O3formation with small amounts of Ga2O3and no detectable As2O3. Third, Cr atoms and O2molecules were condensed onto a Xe buffer layer on GaAs(110) to produce Cr2O3‐like species out of contact with the semiconductor. Buffer layer desorption brought these Cr2O3aggregates into contact with the substrate. The overlayer produced in this manner was abrupt, and there was no evidence of GaAs oxidation.

ISSN:0003-6951    

DOI:10.1063/1.104941

出版商:AIP    

年代:1991

数据来源: AIP