摘要:

The damage formed by 1.25 MeV, self‐ions in Si at liquid nitrogen temperature was studied. A dominant feature of the damage for moderate ion fluences is the presence of isolated amorphous regions over the range of the ions. The microstructure of this damage is detailed and formation mechanisms discussed. The amorphous regions are shown to give rise to strain in the surrounding crystal lattice which varies with ion dose in a complicated manner. The annealing behavior of the damage was studied and two distinct, low‐temperature stages observed. Different mechanisms are shown to be responsible for each stage including a transient mechanism at 300 °C initiated by the release of defects from damage clusters, and enhanced crystallization of amorphous Si at 400 °C due to lattice stress.

ISSN:0021-8979    

DOI:10.1063/1.346561

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Experimental results of enhanced interdiffusion of GaAs‐AlGaAs interfaces are reported. These are obtained by implanting Ar ions at doses ranging from 2×1013to 5×1014cm−2into heterostructure samples followed by rapid thermal annealing at 950 °C for 30 s. The degree of intermixing decreases from the surface up to the projected ion range and is a function of the implantation dose. It is postulated that this variation results from the coalescence of some of the excess vacancies into extended defects, which are then unavailable to assist in the enhanced interdiffusion process. By assuming that the concentration of mobile vacancies at any depth is proportional to the ion’s electronic energy loss and inversely proportional to the ion’s nuclear energy loss, the calculated intermixing results are shown to be in good agreement with the experimental data.

ISSN:0021-8979    

DOI:10.1063/1.346562

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The structural relaxation in (Ni,Fe)75Si10B15metallic glasses has been studied by measuring resistivity changes and Mo¨ssbauer spectra. The sign and magnitude of resistivity changes due to the relaxation depend strongly on the Ni/Fe ratio. The isothermal resistivity changes fit well the nonlinear kinetic form, indicating that the fluctuation of local environments of Ni and Fe atoms is very large and Ni and Fe atoms in Ni‐Fe‐Si‐B metallic glasses are mobile compared with Co and Fe atoms in Co‐Fe‐Si‐B metallic glasses. The compositional dependence and kinetic parameters for reversible resistivity changes and Mo¨ssbauer spectra strongly support that the reversible structural relaxation corresponds to the reversible short‐range ordering between Ni and Fe atoms.

ISSN:0021-8979    

DOI:10.1063/1.346563

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

An ion beam with different incident energiesEwas used to analyze a 500‐A˚‐thick In0.25Ga0.75As strained epitaxial film grown on GaAs (100) by molecular beam epitaxy. Ion channeling angular scans about ⟨110⟩ axis were carried out in (100) plane. WhenEis 5.8 MeV, the angular misalignment between ⟨110⟩ channels of the top layer and the substrate was 0.90°. We can calculate the planar strain of the epilayer, which is 1.62%. When incident ion energy was decreased, anomalous phemomena were observed in the angular scan profiles of the substrate. WhenEis 3.0 MeV, a serious asymmetry appeared in axial scan profile of the substrate; WhenEis 1.2 MeV, the angular misalignment reduced to 0.60°, and the critical angle for channeling of the substrate is 1.25° which is much larger than that of the epilayer, 0.95°. The physical mechanism giving rise to these phenomena is discussed, and the causes and conditions for these phenomena taking place were pointed out.

ISSN:0021-8979    

DOI:10.1063/1.346564

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Thin films of silver selenide (Ag2Se) between thicknesses of about 700 and 2200 A˚ have been prepared on glass substrates at room temperature in a vacuum of 5×10−5Torr. After vacuum annealing the films (at about 373 K for 3 h) electrical resistivity measurements on these films have been carried out in vacuum. From the increase in the rate of decrease of resistance with temperature, the phase transition temperatures (orthorhombic to body‐centered cubic) of the different films have been located. It is found that the phase transition temperature of the thin films is a function of thickness increasing with a decrease in the thickness. This observation has been explained by a recently developed theory [V. Damodara Das and D. Karunakaran, J. Phys. Chem Solids46, 551 (1985)] of phase transitions in thin films modified further. Also, an order‐of‐magnitude value of the difference in the function of specific surface and interfacial energies of the two phases has also been determined using the theory.

ISSN:0021-8979    

DOI:10.1063/1.346565

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Tungsten was deposited from a gas mixture of hydrogen and tungsten hexafluoride onto a polycrystalline silicon gate structure in a chemical vapor deposition system. During the deposition process fluorine was also deposited as an undesired impurity. In order to remove the fluorine, heat treatments in the temperature range 550–1050 °C were performed in a hydrogen atmosphere. By this treatment it is possible to form volatile hydrofluoric acid and hence remove fluorine from the structure. Nuclear‐resonance‐broadening technique and secondary ion mass spectrometry were used for the analysis of fluorine. Fluorine was detected in all the samples except for the sample heat treated at 1050 °C. Moreover, etching of the polycrystalline silicon was observed. The gettering of fluorine, the etching of silicon and the observed formation of tungsten disilicide at 650 °C are discussed with respect to conceivable mechanisms. A thermodynamic study supporting the interpretations is also included.

ISSN:0021-8979    

DOI:10.1063/1.346566

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The interdiffusion and resistivity of Cu/Au, Cu/Co, Co/Au, and Cu/Co/Au thin‐film structures were studied, at temperatures ranging from 25 to 550 °C, using Rutherford backscattering spectroscopy, Auger analysis, and four‐point probe resistance measurements. Intermetallic phase formation was studied by x‐ray diffraction and changes in microstructure were analyzed by scanning electron microscopy. Interdiffusion of Cu and Au in the Cu/Au structure is observed at temperatures as low as 150 °C and is accompanied by an increase in resistivity. No significant reactions occur in the Cu/Co, Co/Au, and Cu/Co/Au thin‐film structures up to 400 °C, after which the resistivity increases. The very rapid increase in resistivity observed at 250 °C for the Cu/Au system and at 450 °C for Cu/Co/Au, is associated with structural changes in the films which result in large grains and the formation of AuCu, Cu3Au, and Cu3Au2compounds. The structural changes in the Cu/Co/Au system occur at a higher temperature because of the time needed for Cu and Au to diffuse through the Co barrier, which did not react significantly with either Au or Cu.

ISSN:0021-8979    

DOI:10.1063/1.346567

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Detailed analytical transmission electron microscopy investigations were performed on a well‐known diffusion barrier system for very‐large‐scale integration metallization. It will be demonstrated that interfacial reactions are of great importance for the barrier mechanism. Both Ti and TiN act as diffusion barrier for the semiconductor and the metallization, respectively. For an aluminum‐based metallization, TiN has a ‘‘spongelike’’ function due to its ability to absorb several amounts of aluminum at elevated temperatures and therefore inhibits diffusion towards the substrate. Ti acts for silicon as a compound forming barrier according to Nicolet’s classification [inTungstenandOtherRefractoryMetalsforVeryLargeScaleIntegrationApplicationsII, edited by E. K. Broadbent (Materials Research Society, Pittsburgh, 1987); pp. 19–26].

ISSN:0021-8979    

DOI:10.1063/1.346568

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The growth of AlxGa1−xP for Al mole fractions between 0 and 1 has been achieved on (100) GaP substrates using gas source molecular beam epitaxy with elemental Ga and Al, and P2cracked from PH3as the source materials. The observed reflection high energy electron diffraction pattern of the GaP surface indicates that an exponential increase in the incident P2flux is required to maintain good morphology beyond 690 °C. This temperature was found to correspond closely to the congruent vaporization temperature of Ga from the growth surface. The addition of Al on the surface was found to substantially increase the Ga congruent vaporization temperature from the GaP surface. The growth rates for AlxGa1−xP as a function of growth temperature between 600 and 750 °C were determined by transmission electron microscopy. Using elemental Si as ann‐type dopant, free electron concentrations as high as 1.65×1019cm−3in GaP and 1.5×1019cm−3in Al0.28Ga0.72P were achieved.

ISSN:0021-8979    

DOI:10.1063/1.346569

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The Al0.05Ga0.95As/Al0.35Ga0.65As single‐ and multiple‐quantum‐well structures with well widths less than 20 A˚ have been successfully fabricated by liquid‐phase epitaxy using low‐temperature, two‐phase, and dummy wafer methods. The transmission electron microscope cross‐section technique is applied to study the thickness variation of quantum well and the transition width at the heterojunction interface. An interesting phenomenon observed during liquid‐phase epitaxy growth is that the interface of Al0.05Ga0.95As grown on Al0.35Ga0.65As is rather flat and sharp whereas the opposite growth sequence gives rise to a wavy interface. It is believed that the flat Al0.05Ga0.95As/Al0.35Ga0.65As interface is due to a tendency to deposit the epilayer when the Al0.05Ga0.95As solution is in contact with the Al0.35Ga0.65As substrate and the wavy Al0.35Ga0.65As/ Al0.05Ga0.95As interface is due to a tendency to dissolve the substrate when the Al0.35Ga0.65As solution is in contact with the Al0.05Ga0.95As substrate. The transition width is less than 10 A˚ at the Al0.05Ga0.95As/Al0.35Ga0.65As interface but is about 30–50 A˚ at the inverted Al0.35Ga0.65As/ Al0.06Ga0.95As interface. These values are about the same as those reported in the recent literature. The peak energy of the photoluminescence spectrum reveals the quantum size effect.

ISSN:0021-8979    

DOI:10.1063/1.346570

出版商:AIP    

年代:1990

数据来源: AIP