摘要:

The growth of high quality AlN and GaN thin films on basal plane sapphire, (100), and (111) silicon substrates is reported using low pressure metalorganic chemical vapor deposition. X‐ray rocking curve linewidths of about 100 and 30 arcsec were obtained for AlN and GaN on sapphire, respectively. Room‐temperature optical transmission and photoluminescence (of GaN) measurements confirmed the high quality of the films. The luminescence at 300 and 77 K of the GaN films grown on basal plane sapphire, (100), and (111) silicon was compared. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114242

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A nanometer‐scale recording technique has been demonstrated on an amorphous GeSb2Te4film with an atomic force microscope (AFM). Data are recorded by locally changing the electrical property of the film with a conductive AFM probe. The conductance of the film is able to be increased more than one hundred times by applying a pulse voltage between the probe and the film. The recorded data are read by detecting the change of the conductance with the probe. The simultaneous measurement of the topographic and conductance images with the AFM shows that the surface topography of the recorded regions is not changed during the recording process. The smallest recorded region is 10 nm in diameter, which corresponds to a data storage density of 1 Tbit/cm2. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114243

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Evidence ofM‐type oxygen octahedral rotations has been observed by transmission electron microscopy in the high‐temperature rhombohedral ferroelectric (FER(HT)) state of Pb(Zr0.95Ti0.05)O3. 1/2{110} superlattice reflections were found to develop on cooling through the dielectric maximum. With further cooling (accompanying a ferroelectric‐antiferroelectric transformation), a gradual transition from 1/2{110} to 1/2{111} reflections was observed. We believe this gradual transition is due to a transformation fromM‐type toR‐type octahedral tilts on cooling. Lattice imaging in the FER(HT)state at room temperature revealed a one dimensionality in the ⟨110⟩ structural modulations. The size of the ordered regions was ∼50–100 A˚. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114244

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Exsituphotoacoustic thermal‐wave imaging of hydrogen electropermeated in a titanium and stainless steel (AISI 304) foil has been performed. Both the magnitude and phase of the complex amplitude of the photoacoustic signal have been investigated. The results show a new phase (TiH2) in the case of titanium and typical blisters in the case of stainless steel; both could be imaged deeply below the sample surface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114245

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

The effect of coherency stresses on the hardness of epitaxial, sputter‐deposited Fe(001)/Pt(001) multilayers was investigated. Coherency stresses were over 2 GPa for films with a bilayer period, &Lgr;, of 44 A˚ and relaxed by more than a factor of 10 for films with &Lgr;=76 and 121 A˚. Since the hardness of these films was constant at approximately 9 GPa over this range of &Lgr;, we conclude that the contribution of coherency stresses to the enhanced hardness is small for this system. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114246

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Data are presented on the electrical behavior and the reliability of postfabrication native‐oxide‐passivated visible‐spectrum AlGaAs–In(AlGa)Pp‐nheterostructure light emitting diodes (LEDs). The LEDs are oxidized (H2O+N2, 500 °C, 1 h) after metallization, thus sealing all exposed AlGaAs crystal at cracks, fissures, and edges against atmospheric hydrolysis without degrading their light‐output characteristics. The current–voltage (I–V) characteristics of the oxide‐passivated LEDs are shown to exhibit normalp‐ndiode behavior (∼1.9 V at 20 mA). The reliability of the oxidized devices in high‐humidity conditions is greatly improved compared to otherwise identical unoxidized LEDs. The latter degrade to less than 50% of initial output power at 1500 h accelerated life test in high‐humidity environments, compared to the oxidized LEDs not degrading noticeably in output power after 2500 h. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114247

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Current flow through Pt/(Ba0.7Sr0.3)TiO3/Pt stack consists of both polarization current and electronic leakage current, which were separated by monitoring the discharging current when applied voltage was turned off. Electronic current comes from electrical field enhanced Schottky emission at the electrode–dielectric interface, and dominates the current flow at high electric field. At low electric field, polarization current prevails. The voltage and time dependence of the polarization current can be modeled by a distribution of Debye‐type relaxations. The relaxation time and capacitance derived from current–time measurements were applied to simulate the current–voltage behavior, where good fitting to experimental result was obtained. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114248

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoluminescence of pseudomorphic Ge wells grown by conventional molecular beam epitaxy on Si substrate is studied. The samples consist ofp‐type doped Gem–Sin–Gemstructures embedded in a Si1−xGexalloy. The luminescence lines shift to lower energy with increasingm, the observed band gap agrees with subband calculation based on an effective mass approximation. The temperature stability of the luminescence depends onm. In the case ofm=4 the luminescence persists up to room temperature with only small reduction in intensity. The activation energies determined from the exponential drop of luminescence intensity agree with band discontinuities in the sample structures. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114249

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We have used x‐ray photoelectron spectroscopy (XPS) to measure the dependence of the InAs/GaSb valence band offset on both interface composition and growth order. Molecular beam epitaxy was used to grow InAs‐on‐GaSb and GaSb‐on‐InAs interfaces with both InSb‐like and GaAs‐like interface compositions. Analysis of XPS core level separations showed no dependence of the valence band offset on interface composition; however, a 90 meV increase in the valence band offset was observed for InAs grown on GaSb compared to GaSb grown on InAs. This difference is attributed to the extended nature of the InAs‐on‐GaSb interface. Results from analysis of an intentionally extended GaSb‐on‐InAs interface were consistent with this conclusion. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114250

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We propose and demonstrate a 1 Gb/s high quantum efficiency Si MSM metal‐semiconductor‐metal detector which is complementary metal‐oxide semiconductor compatible. The detector absorbs over 50% of the light entering the active layer at a wavelength of &lgr;=0.88 &mgr;m. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.114251

出版商:AIP    

年代:1995

数据来源: AIP