摘要:

Thin films of Sr0.5Ba0.5TiO3have been grown on MgO (100), SrTiO3(100), and LaAlO3(012) substrates using pulsed laser deposition. These films were characterized by a variety of x‐ray diffraction techniques. Deposited films exhibited true single crystal morphology. X‐ray rocking curves for the (002) reflection as measured by double and triple crystal spectrometers showed unusually narrow full width at half‐maximum (FWHM) values of 72 arcsec for films grown on LaAlO3, and 140 arcsec for films deposited onto SrTiO3. The FWHM for films deposited on MgO were significantly broader (∼2500 arcsec). While the quality of the epitaxial films is related to the lattice mismatch between the film and the substrate, extremely well aligned films can be grown on substrates with a relatively large lattice mismatch.

ISSN:0003-6951    

DOI:10.1063/1.113866

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Highly oriented thin films (0.15 &mgr;m) of titania on Si (100) substrates have been prepared first by hydrothermal treatment of TiO42−solution (0.6–1.2M) at relatively low temperatures. Films made at 100–200 °C contain only the anatase phase with (112) orientation, adhere well to the substrates. The hydrothermal temperature, time, and thepH value of TiO42−solution are the critical parameters determining the formation of films. ©1995 American Institute of Physics. 

ISSN:0003-6951    

DOI:10.1063/1.113867

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Insituthin films of (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3, (PMN‐PT), with compositionx=0.1, 0.3, 0.35, and 0.4, were deposited on MgO(100) substrates by pulsed laser deposition. The optimum conditions to form (100) oriented PMN‐PT perovskite phase were at substrate temperatures in the range of 535 to 575 °C with an oxygen pressure of 200 mTorr. The Mg content in PMN‐PT films was found to be essential to the formation of perovskite phase. Heterostructures of PMN‐PT/La0.5Sr0.5CoO3(LSCO) films were prepared on MgO(100) substrates to evaluate the dielectric properties of the films. The dielectric constant of PMN and PMN‐PT films ranged from 1000 to 3800 at 10 kHz measured at room temperature. The highest dielectric constant was obtained from PMN films with 99% perovskite phase. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113868

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

An external cavity semiconductor laser that incorporates a large‐area amplifier has been successfully stabilized into a single transverse mode over the 600 &mgr;m width of the amplifier. Single‐transverse‐mode operation is achieved by using the combination of a diffractive mode‐selecting mirror and an aperture. 2.8 W of stable diffraction‐limited output power is achieved. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113869

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Performance capabilities of reflectometers and ellipsometers for determining near‐surface dielectric properties by virtual‐interface analysis of kinetic data are calculated for the prototypical semiconductor alloy Al0.30Ga0.70As. Measurement of phase as well as amplitude improves relative sensitivities by over an order of magnitude. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113870

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We utilize the sensitivity of the two‐ to three‐dimensional growth transition of InAs self‐assembled islands on InAs coverage to demonstrate the growth of self‐aligned InAs islands on etched GaAs ridges by molecular beam epitaxy. The different migration behavior of In adatoms on different crystal planes of etched ridges is used to spatially modulate the supply of In adatoms. The ridges are oriented either along the [011] and [011¯] direction on (100) substrates with grating spacing of 0.28, 1, and 5 &mgr;m. Atomic force microscopy reveals that the InAs islands are self‐aligned along the ridges and they have a typical size of 400 A˚ in diameter and 120 A˚ in height. In samples with [011] oriented ridges, the islands are located on the sidewalls. On the other hand, for [011¯] oriented ridges the islands are on the (100) planes on and at the foot of the mesa. On samples with a grating pitch of 0.28 &mgr;m, all the islands are located either on the sidewalls or at the bottom of the ‘‘V groove’’ for both grating orientations. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113871

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have performed Monte Carlo simulation of electronmagnetotransportin a GaAs quantum wire at 77 and 300 K. At sufficiently high electric fields, a magnetic field was found to enhance the electron drift velocity significantly by preferentially suppressing backscattering events. Moreover, the field also decreases the electron temperature (suppressing it wellbelowthe lattice temperature at 300 K over a wide range of electric field) which reduces Johnson noise. Surprisingly, the electron temperature islowerat a lattice temperature of 300 K than at a lattice temperature of 77 K when a magnetic field is present. All of these have important implications for the transconductance, unity gain frequency and noise margin of quasi‐one‐dimensional electronic devices such as quantum wire field effect transistors. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113872

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The reconstruction and the step structure change during the phase transition on an InAs(001) surface under As pressure is observed directly by using scanning electron microscopy. The domain formation corresponding to the first‐order phase transition is clearly seen as predicted by Monte Carlo simulation with a lattice gas model. It is also seen that the step structure largely depends on the surface reconstruction and the misorientation direction. This gives the first observation of phase‐transition‐induced step bunching on a compound semiconductor surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113873

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Electrical pulses from 450 fs to 3 ps are generated using coplanar strip lines and coplanar waveguides on SI GaAs substrate. We use two optical pump beams to generate two steplike electrical transients with opposite sign and then superimpose the signals resulting in rectangular shaped pulses. By varying the delay between the two pump beams the pulse width can be adjusted. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.113874

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

InxGa1−xN (x=0.07–1.0) layers were grown on GaAs substrates by metalorganic molecular beam epitaxy. The films display strongn‐type conductivity (n≳1020cm−3) for a wide range of compositions. The use of an H2rather than a He carrier gas produces a lower carrier concentration in the as‐grown material. The InxGa1−xN is single crystal at low Ga concentrations with the lattice mismatch accommodated by a high density of stacking faults and microtwins. The InN layers contain only the cubic phase, while the ternaries contain both cubic and hexagonal phases.

ISSN:0003-6951    

DOI:10.1063/1.113875

出版商:AIP    

年代:1995

数据来源: AIP