摘要:

The crystalline to amorphous transition in As and Sb and the corresponding changes in physical properties primarily arises from modifications in the second neighbor distributions. Raman scattering measurements in amorphous &bgr;‐As, &ggr;‐As, and a‐Sb are reported that further indicate a progression from quasi‐molecular to nonmolecular character in this series as manifest in the polarization properties of the spectra. It is suggested that this transition indicates variations in structure and reflects an increase in second neighbor interactions in a‐Sb. A comparison of Raman and neutron scattering measurements in &bgr;‐As is used to yield information about the frequency dependence of the Raman coupling parameters beyond the elastic continuum regime.

ISSN:0094-243X    

DOI:10.1063/1.30740

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The diamagnetic susceptibility and the optical properties, reflectivity and refractive index, are powerful probes of chemical bonding in semiconductors. The reflecitivity and its pressure derivative have been measured in the photon energy range 0.5 eV to 4.5 eV. The magnetic susceptibility and its temperature derivative are consistent with a model which describes the bonding in a‐As as p‐like. Measurements of expansion coefficient and the temperature derivative of refractive index are also reported.

ISSN:0094-243X    

DOI:10.1063/1.30741

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

It is demonstrated how the radial distribution function of a triply coordinated random network can be synthesised from the ring statistics and the distributions of bond angles and dihedral angles. Problems peculiar to three‐fold coordination are discussed in relation to the distribution of pairs of atoms connected by three bonds and the background distribution of more distant neighbors.

ISSN:0094-243X    

DOI:10.1063/1.30742

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

A two‐dimensional amorphous lattice has been constructed using the generalized random walk technique. The bond lengths and angles were obtained from the random number generation functions. The lattice sites were assumed to have a coordination number of three and were connected to form closed polygons. The lattice and the associated structural properties are calculated. A lattice dynamical calculation is then performed using this network as a two‐dimensional amorphous structural representation. The explicit vibrational spectra are obtained for the random network and the corresponding three‐fold‐coordinated honeycomb lattice.

ISSN:0094-243X    

DOI:10.1063/1.30743

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Reversible photo‐induced structural changes observed in evaporated chalcogenide films are discussed on the basis of the results of X‐ray diffraction and volume change measurements. In situ optical measurements performed at 14K for evaporated As2S3are also shown, which is discussed in connection with the photo‐induced optical absorption in melt‐quenched Ad2S3.

ISSN:0094-243X    

DOI:10.1063/1.30744

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The microscopic investigation of structural changes of bulk chalcogenide glasses and evaporated amorphous films by annealing and photoirradiation is carried out by the change of the ESR spectrum Mn doped as probe. The signal is found to change by the composition of the sample and by annealing. The change of the signal appears to be caused also by photoirradiation, but the reproducibility could not be established at the present stage. Although the present work is preliminary and a full understanding has not yet been achieved, the investigation of the change of the ESR signal is believed to be very useful in understanding the structural change from the microscopic point of view.

ISSN:0094-243X    

DOI:10.1063/1.30745

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

The Fourier transform, &fgr; (r), of the EXAFS is expressed as the convolution of a structure factor and a scattering factor. We show that the extraction of a structure factor from &fgr; can be hampered substantially by the long range and oscillatory nature of the contribution by each shell. Specific procedures are recommended to inrease the reliability of using &fgr; (r) to obtain structural information, and their implementation is illustrated for crystalline Ge. The implications of the differences in &fgr; between an amorphous solid and its crystalline analog are discussed.

ISSN:0094-243X    

DOI:10.1063/1.30746

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

It is shown that one can obtain information about higher order structural correlations if one analyses the conditions under which vibrations of a network can be decoupled, and compares them with the Raman and i.r. data. The method applied to amorphous As2S3and As2Se3gives the ordering of the basic structural elements‐AsX3pyramids. It resolves a controversy about the structure of these glasses and clarifies its relationship to the crystalline structure.

ISSN:0094-243X    

DOI:10.1063/1.30748

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

We reexamined the strong compositional dependence of the conductivity &sgr; discovered by Ferrieretal. in TemT12films. We found the optical gap and the activation energy of &sgr; to be independent of m. At low T an extrinsic conduction occurs near m=2.5 and 3.5. The defect states causing this are removed by annealing in clean films. Annealing is prevented by one atomic percent oxygen.

ISSN:0094-243X    

DOI:10.1063/1.30749

出版商:AIP    

年代:1976

数据来源: AIP

摘要:

Structural considerations based on chemical bond strength allow us to predict the nature and the number of bond versus X. Application of the Anderson concept of electron pairing to dangling bonds leads to polar states. We predict the nature and the number of such polar states versus X. This mode is tested by studying the variation of the Urbach tail with temperature and composition. The Urbach tail comes from internal microfield, arising, here, from polar states and optical phonons of the Ge‐Te bonds. The qualitative variations of their number with X can be deduced from experiments. They are in agreement with the postulated model of electron pairing.

ISSN:0094-243X    

DOI:10.1063/1.30750

出版商:AIP    

年代:1976

数据来源: AIP