摘要:

Process of epitaxial growth of PbSe on SnTe (001) under UHV condition is studied with the use of glancing angle scattering of MeV He ions and transmission electron microscopy. An empirical relationship of the mean separation of misfit dislocations on the PbSe/SnTe interface and the thickness of the layer is derived from TEM observation. Anomalous broadening of the angular distribution of scattered He ions from the surface of PbSe is observed when the thickness of the PbSe layer is between 1 and about 20 nm. From the simulation of ion trajectories at glancing angle scattering from several model surfaces, this anomaly is attributed to the surface wrinkles caused by a square-net of misfit edge dislocations.

ISSN:1042-0150    

DOI:10.1080/10420159108221349

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Positron lifetime and Doppler broadening measurements have been performed in homogeneously helium implanted (715 appm) molybdenum. A new stage beyond the temperature range of stability of voids has been observed. The shorter lifetime componet τ1= 158 ± 2 ps of 60% intensity is assigned to the positron state in helium-decorated dislocation loops while the longer lifetime component τ2= 408 ± 5 ps of 40% intensity is explained in terms of positron trapping at voids with a small percentage of helium associated with them. Dissociation of helium from loops is observed in the range 300–800 K followed by loop annealing above 900 K. A sharp reduction of τ2around 1300 K is assigned to multiple helium occupancy of voids, resulting in their transformation into stable bubbles. Helium retention in bubbles is found stable up to the highest annealing temperature of 1700 K. The bubble parameters deduced from the positron lifetime results reveal that the pressure in the bubbles is maintained at the near-equilibrium value and that the vacancy mode of bubble growth is operative, in contrast to the reported growth of athermal bubbles in molybdenum following very low energy helium implantation where loop punching mechanism seems to control the excess pressure in bubbles. A brief comparison is also made between the observed behaviour of helium with that of hydrogen in molybdenum and the differences are discussed.

ISSN:1042-0150    

DOI:10.1080/10420159108221350

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Irradiation studies on H-charged Y-Ba-Cu-O films were performed for the first time. Samples, produced by laser ablation, were charged by H and irradiated successively at low temperature with 7 MeV15N ions.In situresistivity measurements were carried out below 100 K after each irradiation step. To determine the H concentration the nuclear reaction1H(15N, αγ)12C was used. For all samples (with different H concentration) an almost linear correlation between fluence and decrease of the critical temperature (Tc) was found. Changes inTcwith increasing H-concentration show, that H makes Y-Ba-Cu-O superconductor films more sensitive to heavy ion irradiation.

ISSN:1042-0150    

DOI:10.1080/10420159108221351

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Changes in dopant concentration profiles in crystalline silicon induced by rf hydrogen plasma treatment of Si-SiO2structures were studied by using differential capacitance technique. It was found that such a treatment influences p-type and n-type silicon controversially. In p-type Si compensation of boron acceptors by neutral H-B complex formation was observed. It was suggested that the increase of doping concentration in n-type Si is due to the generation of donor-like defects in the bulk Si by plasma radiation.

ISSN:1042-0150    

DOI:10.1080/10420159108221352

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The electron paramagnetic resonance of divalent Mn2+ions in the Tutton salt ZnTl2(SeO4)2· 6H2O single crystals has been observed at room temperature and liquid nitrogen temperature using X-band microwave frequency. The Mn2+has been found to substitute for Zn2+exhibiting two magnetically inequivalent complexes. The EPR spectra have been analyzed using the spin-Hamiltonian appropriate for rhombic symmetry.

ISSN:1042-0150    

DOI:10.1080/10420159108221353

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The influence of γ-ionizing radiation on floating gate (FG) MOS transistor (MOST) having a positively or negatively charged FG has been studied. It is shown that a transistor with negatively charged FG may be used for dosimetry measurements.

ISSN:1042-0150    

DOI:10.1080/10420159108221354

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

The paper discusses the results of studying reflection dynamics from the surface of monocrystalline semiconductors Si, Ge, GaAs during irradiation by nanosecond (<102nsec) laser pulses (<1=0.53 μm, <2=1.06 μm) with incident energy density exceeding the semiconductrs melting threshold.

ISSN:1042-0150    

DOI:10.1080/10420159108221355

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

Thermoluminescence processes in KCl:Ag (14 ppm) crystals following room temperature γ-irradiation (20 Mrad for 50 h) has been examined. Silver impurities induce “shallow” traps and the processes follows neither the first-order nor the second-order kinetics. Recombination processes show both intrinsic factors (460 nm) and extrinsic factors (263 nm and 700 nm). Electron-hole recombination occuring at some stage during interstitial-F-centre recombination, favours tunneling.

ISSN:1042-0150    

DOI:10.1080/10420159108221356

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

摘要:

We review studies of the effects of electronic excitation in α-Al2O3crystals, paying special attention to the problem of the existence of self-trapped excitons and self-trapped holes in the material. After a brief review on the crystallographic and electronic structures, information on thermal and radiation-induced defects is summarized. The concept of self-trapping of holes is critically reviewed and the possible contribution of the native acceptor impurities in the processes which have been attributed to the self-trapped holes is discussed. Experimental observations on the so-called intrinsic luminescence in α-Al2O3crystals is surveyed and again the possible contribution of native impurities is discussed. The relaxation processes of electronic excitation in α-Al2O3crystals are compared with those in MgO and SiO2having similar physical and chemical properties but differeing in the crystallographic and electronic structures. The properties of metastable defects induced by electronic excitation are discussed in connection with the recently discovered transient volume expansion effect under the excitation by short electron pulses.

ISSN:1042-0150    

DOI:10.1080/10420159108221357

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor

ISSN:1042-0150    

DOI:10.1080/10420159108221358

出版商:Taylor & Francis Group    

年代:1991

数据来源: Taylor