摘要:

Epitaxial Ge films have been deposited at 300 °C using a remote plasma‐enhanced chemical‐vapor deposition technique where metastable He atoms flow downstream from the plasma region to dissociate GeH4molecules into deposition precursor species. Ge epitaxy is demonstrated on Ge(111), Si(100), and GaAs(111)Ga face substrates. Aninsitucleaning process that involves a moderate thermal bake at 300 °C and a hydrogen plasma etch of the native oxides is integral to the process. Reflection high‐energy electron diffraction is used to examine surface quality just prior to and after deposition. Uniform integral order diffraction streaks and fractional order reconstruction features observed from the Ge epilayers indicate that high quality Ge epitaxial layers can be grown using remote plasma‐enhanced chemical‐vapor deposition.

ISSN:0021-8979    

DOI:10.1063/1.337604

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Single crystals of Nb‐Ta superlattice have been grown by molecular‐beam epitaxy. The epitaxial relations between the samples and several kinds of sapphire substrates have been determined using x‐ray diffraction. The interface region between Nb and Ta layers is estimated to be about 6 A˚. A terraced structure of the superlattice is discussed. Reflection high‐energy electron diffraction patterns of Nb and Ta surfaces observedinsitushow half‐order streaks and an elongation of lattice constant in the growth direction.

ISSN:0021-8979    

DOI:10.1063/1.337605

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Thin films of amorphous/polycrystalline Ti layers alternating with amorphous Si have been grown on room‐temperature {001} Si substrates by electron beam evaporation. Cross‐section transmission electron microscopy of these films indicates that the deposition results in the formation of ultrathin superlattice layers with no cumulative roughening and with atomically abrupt interfaces. The crystallinity of the layers containing Ti is found to depend on the layer thickness. For thicknesses ≤20 A˚ they appear amorphous, whereas layers thicker than ∼40 A˚ consist of polycrystalline hexagonal Ti grains exhibiting a (0001) preferred orientation parallel to the interfaces.

ISSN:0021-8979    

DOI:10.1063/1.337606

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A modification to accommodate loss is made to a method developed by D. Murray and E. A. Ash [1977UltrasonicsSymposiumProceedings, IEEE Cat. No. 77CH1264‐1SU (IEEE, New York, 1977), p. 823] for computing the surface acoustic wave slowness surface of piezoelectric substrates. The resulting algorithm is used to determine the slowness surface for the leaky or pseudosurface wave which propagates on [100]‐cut GaAs and for a cut 5° off from this. The data thus obtained are used in a diffraction theory computer program to predict the shape of beam profiles as they propagate in the substrate material and accurate predictions of beam shapes are obtained.

ISSN:0021-8979    

DOI:10.1063/1.337607

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The liquid‐phase epitaxy (LPE) growth of InGaPAs grown on (100) GaAs substrate has been studied under various growth conditions over the whole solid composition range. It has been found that the degree of supercooling less than 5 °C is necessary to successfully grow InGaPAs LPE layers in the composition region influenced by immiscibility, and that the extraordinary broadening of their photoluminescence spectra is attributed to a large number of defects and dislocations included in them. The role of the elastic energy induced from a substrate is discussed on a basis of the experimental results of the InGaPAs LPE growth on GaAs. The degree of immiscibility is also discussed using the regular solution approximation.

ISSN:0021-8979    

DOI:10.1063/1.337608

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A cross‐sectional transmission electron microscope (XTEM) study of solid phase epitaxial growth in BF+2‐implanted (001)Si has been carried out. It is demonstrated that XTEM is unique in providing accurate, high‐resolution data on the regrowth of implantation‐amorphous layer. The activation energy for the regrowth was measured to be 3.0±0.1 eV. Uncertainties in the XTEM measurements of solid phase regrowth rate are discussed.

ISSN:0021-8979    

DOI:10.1063/1.337609

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

A nondestructive method to determine the diffusion length of minority carriers in ap‐silicon wafer is outlined. This novel method is based on creating an accumulation layer on one side and an inversion layer on the other side of the wafer by depositing thin semitransparent layers of high (e.g., palladium) and low (e.g., aluminum) workfunction metals, respectively. The wafer acquires a structure akin top+‐p‐n+and is capable of generating a photocurrent when illuminated. The photocurrentIsc(where sc represents short circuit) as a function of the intensityPinof a monochromatic radiation incident on the accumulation layer (p+) side of the wafer is measured. The diffusion lengthLis determined from the slope of theJscvsPincurve. The values ofLso determined were compared with that determined from the measurement of spectral response by illuminating the wafer from the inversion layer (n+) side and were found to be in excellent agreement.

ISSN:0021-8979    

DOI:10.1063/1.337610

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

Measurements on a variety of doped (magnesium and/or iron) and undoped lithium niobate crystals in the oxidized state demonstrate an Arrhenius dependence of dark conductivity on reciprocal temperature between 460 and 590 K. All of the crystals had roughly the same conductivity and activation energy (1.21 eV) over the temperature range, implying that all have about the same free‐carrier concentration and mobility. The enhanced photoconductivity of magnesium‐doped lithium niobate is attributed to a greatly reduced trapping cross section of Fe3+for electrons, the smaller cross section being due to a changed substitutional site for Fe3+. The Fe3+trapping cross section is calculated from photoconductivity data to be of order 10−18m2in undoped lithium niobate. This implies a photoelectron lifetime of order 6×10−11s in a relatively pure (2‐ppm Fe) oxidized crystal.

ISSN:0021-8979    

DOI:10.1063/1.337611

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

The study of the excess conductivity induced in a material by pulsed optical excitation yields information on the optoelectronic properties of the material and is receiving increasing attention. As conventional conductivity techniques are hampered by the need to apply electrical contacts, we have investigated the reliability and the possibilities of microwave conductivity measurements. This paper first presents the general background for excess conductivity measurements in the microwave range, and then derives the quantitative relationship between the reflected microwave signal and the change in conductivity for a wafer of single‐crystalline Si. For this sample, the theory of excess charge carrier kinetics is also developed. After a short description of our apparatus, kinetic measurements on a nano‐ and microsecond timescale are compared to theory.

ISSN:0021-8979    

DOI:10.1063/1.337612

出版商:AIP    

年代:1986

数据来源: AIP

摘要:

High‐dose silicon implants have been used to preamorphize the surface of single‐crystal silicon prior to the implantation of low‐energy BF2. The preamorphization results in shallow junction formation with minimal channeling of the boron, but high concentrations of electrically active defects are formed, leading to excessive reverse bias leakage currents. Measurements of leakage current and deep‐level defects indicated that two distinct types of electrically active defects were important: those associated with what are probably complexes or clusters of point defects located near the far end of the range of the implanted silicon, and those associated with extended defects (loops) at the edge of the regrown amorphous region. The former defects were deep‐level donors present in high concentrations (>1017cm−3) after regrowth of the amorphous layer at 600 or 700 °C and resulted in leakage currents >10−4A/cm2. These centers could be annealed out at 800 °C reducing the leakage current to values between 5×10−8and 2×10−5A/cm2depending upon the relative locations of the extended defects and the metallurgical junction. Measurements and modeling have shown that the location of the band of extended defects is critical in controlling the leakage current and that it will need to be a few hundred angstroms shallower than the junction itself for the associated generation current to be fully suppressed.

ISSN:0021-8979    

DOI:10.1063/1.337613

出版商:AIP    

年代:1986

数据来源: AIP