摘要:

Extraction energies for diamond and zinc‐blende semiconductor compounds and pseudobinary alloys are calculated using a tight‐binding cluster method, where the final state of the removed atom is in a free‐atom state. The extraction energies provide a convenient reference from which other final states of the removed atoms can be calculated. In the elemental and compound semiconductors, the convergence of the cluster calculation was verified using a Green’s function calculation with the same Hamiltonian. For the elemental semiconductors, vacancy (or Schottky defect) formation energies, in which the final state of the removed atom is on the surface, have been calculated. For pseudobinary alloys of the formA1−xBxC, we find extraction energies to be very sensitive to the local environment, exhibiting a nonlinear variation between theA‐ andB‐rich local environments; the nonlinearity is especially pronounced for the removal of aCatom. Nonlinearities are found to arise primarily from the occupation of localized vacancy states. The impact that these alloy variations will have on measurable properties are discussed.

ISSN:0021-8979    

DOI:10.1063/1.347069

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

The passivation and dissociation process of the hydrogen‐Si donor complex in plasma‐hydrogenated GaAs was presented. The temperature dependent values of dissociation frequencies &ngr;dwhich the first‐order kinetics permit, satisfy the relation &ngr;d=5.7×1013 exp(−1.79±0.05eV/kT) s−1for the no‐biased anneals. During electric‐field‐enhanced anneal experiments, we confirm that no in‐diffusion from the passivated region to the bulk is observed in the temperature ranges below 150 °C, and that there is a dissociation frequency region independent of the annealing temperature. Finally, from the electric field annealing experiment on the passivated donor inn‐type GaAs, it is suggested that the hydrogen atom in Si‐doped GaAs exposed to the plasma hydrogen is negatively charged with the gain of free electrons and passivates the Si donor, and also that the hydrogen atom or the electron of the hydrogen‐Si donor complex can be easily released by the electric field.

ISSN:0021-8979    

DOI:10.1063/1.347070

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A possible correlation between the annealing of secondary defects in silicon with high P background and anomalous diffusion of As or Sb was investigated. The P background (9×1019–4×1020cm−3) was formed by phosphorus implantation (80 keV (2–10)×1015cm−2), followed by rapid thermal annealing. Dislocation loops and misfit dislocations of various densities were formed under these conditions. Subsequently, As or Sb was implanted, and finally the crystals were annealed by rapid thermal annealing. By a combination of Rutherford backscattering/channeling, transmission electron microscopy and Hall measurements, anomalous diffusion of Sb and As and reduction or complete annealing of the secondary defects were found in the presence of the high P background. The results are discussed in terms of interaction between impurities and dislocations or defect complexes.

ISSN:0021-8979    

DOI:10.1063/1.347071

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Deep‐level transient spectroscopy (DLTS) and capacitance‐voltage (C‐V) measurements have been used to study the residual defects inn‐type AlGaAs co‐implanted with Be and either As or P. The co‐implant procedure is being studied as a method for limiting Be diffusion during the rapid thermal annealing process used to activate the Be. The only defect found in the upper half of the band gap by DLTS measurements between 10 and 450 K has an activation energy of 0.88 eV. This defect undergoes photocapacitance quenching, which together with its activation energy suggests that it is similar to the EL2 defect found in GaAs. In an analysis of high‐temperatureC‐Vdata, the defect manifests itself as a peak in the donor concentration. The donor concentration data were modeled by doing a double integration of Poisson’s equation assuming a Gaussian defect distribution and a uniform shallow donor distribution. This analysis indicates that the center of the Gaussian defect distribution is near the peak in the P or As distribution and that the peak concentrations are about 1×1017defects cm−3for the higher P and As fluences.

ISSN:0021-8979    

DOI:10.1063/1.347072

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Ionizing radiation and sweeping modify the defects present in quartz. According to relaxation theory the modification should produce a fractional frequency offset, &Dgr;f/f, equal to the negative of the sum of the changes in strength of the acoustic loss peaks with peak temperatures below the turnover. We have measured the acoustic loss and frequency versus temperature curves as functions of radiation dose, and alkali and hydrogen sweeping for AT‐cut cultured quartz crystals with widely varying aluminum concentrations. The largest offsets were observed for the Na‐swept crystals and the smallest for the H‐swept samples. In addition, the smallest radiation‐induced offsets were found in swept crystals with the lowest Al content. The magnitude of &Dgr;f/fwas different from that predicted by relaxation theory. Instead, the observed &Dgr;f/fat the turnover consisted of: (1) the expected relaxation component, (2) a &Dgr;f/fat low temperatures in all samples studied, and (3) a change in the overallf(T) curve which appears only in Na‐swept crystals. The lowToffset is caused byT‐independent changes in the elastic modulus. These must be due to the modifications of the interatomic forces brought about by the radiation‐induced defect changes. Our general findings support the use of swept low‐aluminum quartz in radiation environments.

ISSN:0021-8979    

DOI:10.1063/1.347046

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

X‐ray reflectivity measurements were made on Si(001) crystals containing a delta‐doping layer of Sb atoms a few nanometers below the surface. The measurements show the Sb doping profile to be abrupt towards the substrate side of the sample and to decay towards the surface with a characteristic decay length of 1.01 nm.

ISSN:0021-8979    

DOI:10.1063/1.347047

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

We derive an expression for the dislocation line tension in thin‐film structures for double‐kink (dislocation dipole) extension of a threading dislocation. From these calculations, we conclude, that for a double kink that is a distance of more than three times the vertical dipole separation from the free surface, the effect of the free surface on the double‐kink line tension is insignificant. We consider the specific case of a double‐kink bounding a 60‐nm‐thick Si0.7Ge0.3strained layer grown on a silicon substrate and buried under a silicon cap. For this specific configuration, line tension is seen to increase with cap thickness (which is equivalent to distance of the double kink from the surface) only up to a cap thickness of 100 nm.

ISSN:0021-8979    

DOI:10.1063/1.347048

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

A systematic study, investigating the effects of strained‐layer superlattices (SLSs) on threading dislocations present in GaAs/Si heteroepitaxial layers, was conducted. Transmission electron microscope contrast analysis was performed on ∼1% lattice‐mismatched GaAs0.72P0.28/GaAs SLSs grown on GaAs/Si substrates.Threading dislocations were found to have Burgers vectors inclined to the GaAs/Si interface. Individual strained layers ranging in thickness from 100 to 250 A˚ were observed to have negligible effect on dislocation bending. Instead, dislocation bending occurred primarily at the first and last interfaces of the SLS packets. Similarly, effective dislocation bending was observed using 1000 A˚ layers. Threading dislocation density close to the GaAs/Si heterointerface was found to depend on the SLS packet proximity to the interface.

ISSN:0021-8979    

DOI:10.1063/1.347049

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Expressions for the piezoelectric corrections to the second‐ and third‐order coupling parametersK2andK3in cubic, rhombohedral, tetragonal, and orthorhombic crystalline structures are presented. The corrections depend on the linear and nonlinear dielectric constants, second‐ and third‐order piezoelectric moduli (which are related to the elasto‐optic, electrostrictive, and the electroacoustic coefficients). The corrections are estimated for the cases of crystalline quartz and lithium niobate.

ISSN:0021-8979    

DOI:10.1063/1.347050

出版商:AIP    

年代:1990

数据来源: AIP

摘要:

Thermal conductivities of InSb and GaSb in solid and liquid states were measured with a ceramic probe. Thermal conductivities at melting points were about 17.7 (W/mK) at 803 K for molten InSb and 21.7 (W/mK) at 993 K for molten GaSb. Thermal conductivities were slightly increased with increasing temperature in liquid state. Lorenz numbers in liquid state were 2.34×10−8(W&OHgr;/K2) at 803 K for InSb and 2.07×10−8(W&OHgr;/K2) at 993 K for GaSb.

ISSN:0021-8979    

DOI:10.1063/1.347051

出版商:AIP    

年代:1990

数据来源: AIP