摘要:

We observed an anomalous temperature effect for poly(cyclohexylmethylsilane) (PHMS) in a systematic study on formation of electrically oriented polysilane films by casting on interdigital electrodes to which a dc voltage is applied. The orientation of PHMS is quite sensitive to the process temperature: polysilanes align well along the electric field at 14 °C but do not at temperatures higher than 15 °C or lower than 11 °C. It is also shown that the degree of orientation of polysilanes in the films reflects to the electric conduction. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115187

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

X‐ray rocking curve measurements showed a significant crystallographic tilt in relaxed InGaAs layer grown on (001) GaAs. Transmission electron microscopy revealed that the origin of tilt is 60° dislocations generated having Burgers vectors of a same vertical edge component. Calculations using anisotropic elasticity show that this configuration of 60° dislocation array is energetically favorable when the tilt of epilayer is present as to remove the long range stress field induced by the vertical edge components at the interface. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115188

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Photoconductivity (PC) spectroscopy is used to determine the optical absorption and behavior of free carriers of Si/Ge structures and (Si6Ge4)100superlattices grown on Si0.4Ge0.6alloys. Negative photoconductivity is observed at a temperature of 67 K. Some samples are additionally doped by nuclear transmutation. These samples exhibit a strong negative PC signal even at room temperature, which cannot be suppressed by a bias illumination. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115189

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Vibrational modes of carbon doped InP have been investigated by Raman scattering and cluster‐Bethe‐lattice calculations. In contrast to other carbon doped III–V semiconductors, the InP samples grown by metalorganic molecular beam epitaxy (MOMBE) shown‐type conductivity. Raman spectra from such samples reveal a vibrational mode at 220 cm−1. The frequency of this mode lies in the gap between the acoustic and optical branches of the phonon dispersion (gap mode). Cluster‐Bethe‐lattice calculations predict such a gap mode only for the carbon donor on the In site and not for the carbon acceptor on the P site. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115190

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

A method for silicon surface preparation prior to wafer bonding is presented. By cleaning the wafers in a H2SO4:H2O2mixture in which a small amount of HF is added, and then rinsing in H2O, the bonding behavior of the surfaces is improved, compared to other pretreatments used for bonding. The modified SPM cleaning results in a highly fluorinated chemical oxide on the Si surface. A subsequent water rinse causes substitution of F by OH groups, which increase the initial attraction of the mating surfaces. Higher contact wave velocities and bond strengths than reported for other surface pretreatments have been measured, both for bare and thermally oxidized silicon surfaces. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115191

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

CuxS nanocrystals (NC’s) are reported. The samples are prepared by a CdS‐to‐CuxS chemical conversion from the glasses originally containing CdS NC’s. A room‐temperature linear absorption of the converted samples shows several well resolved peaks with spectral positions from red to blue. These spectral features are explained by size quantization within CuxS NC’s (∼4 nm radius) with different copper deficiency [xis in the range from 1.8 (digenite) to 2 (chalcosite)]. A strong bleaching of the samples with a 3‐ns relaxation is observed in the pump–probe measurements. A high value of the third‐order nonlinear susceptibility (∼10−7esu) is derived from the nonlinear transmission spectra. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115192

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

Strained GaSb quantum dots having a staggered band lineup (type II) are formed in a GaAs matrix using molecular beam epitaxy. The dots are growing in a self‐organized way on a GaAs(100) surface upon deposition of 1.2 nm GaSb followed by a GaAs cap layer. Plan‐view transmission electron microscopy studies reveal well developed rectangular‐shaped GaSb islands with a lateral extension of ∼20 nm. Intense photoluminescence (PL) is observed at an energy lower than the GaSb wetting layer luminescence. This line is attributed to radiative recombination of 0D holes located in the GaSb dots and electrons located in the surrounding regions. The GaSb quantum dot PL dominates the spectrum up to high excitation densities and up to room temperature. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115193

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

We present an analysis of optical data from ZnSe strained‐layer quantum wells surrounded by Zn1−xMgxSySe1−ybarrier layers to extract the band offsets. If we use only the ground state transitions from our experimental data, no unique value of the offset can be obtained: a direct consequence of the fact that there are no uniquely agreed upon values of the effective masses for ZnSe available. However, if we include the excited states, only one out of six considered sets of effective masses gives a reasonable fit to the experimental data, giving the conduction band offset of only 10% of the band gap difference. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115194

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

In oxygen‐rich GaAs the optical absorption of substitutional oxygen (OAs) in the near infrared was investigated by measuring its magnetic circular dichroism (MCDA). An MCDA was discovered which originates from a paramagnetic ground state. By investigating its thermal decay kinetics and its dependence on optically induced recharging processes involving EL2 defects and by comparison with analogous local vibrational mode measurements, it could be shown that the MCDA is due to the metastableB′ charge state of the OAscenters. TheB′ state is thus identified as the paramagnetic charge state of the OAscenter. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115195

出版商:AIP    

年代:1995

数据来源: AIP

摘要:

GaN films were prepared by hot wall epitaxy on sapphire (0001) substrates from Ga and NH3sources. Growth characteristics of the GaN films were investigated from reflection high energy electron diffraction (RHEED) and x‐ray diffraction measurements, and effects of initial layers on the film growth are discussed. High quality films with streak RHEED patterns were obtained when the films were grown on a GaN initial layer prepared by Ga predeposition and its nitridation on surface nitrided sapphire substrates. ©1995 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.115196

出版商:AIP    

年代:1995

数据来源: AIP