摘要:

The surface morphology of GaAs layers on (001) InAs substrates, grown by MOVPE at temperatures in the range 500–650 °C and for times from a few seconds to minutes, has been observed by atomic force microscopy. Information on the strain release and on the surface quality has been obtained by Raman scattering and high resolution x‐ray diffraction measurements. Large islands with different shapes and facets are generally formed and only at 550 °C is a quasi‐2D growth observed. At the highest growth temperatures InxGa1−xAs is detected at the interface. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117094

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

A hybrid acoustic spectroscopy technique has been used to demonstrate the (reversible) conversion of high frequency electric fields into longitudinal acoustic waves within a modulation‐doped pseudomorphic Si/Si0.88Ge0.12/Si heterostructure. This provides compelling evidence for the existence of a piezoelectriclike coupling within such structures. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117095

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

High quality Al0.15Ga0.85N/GaN heterostructures have been fabricated on 6H–SiC and sapphire substrates by metalorganic vapor phase epitaxy (MOVPE). A temperature independent mobility, indicative of the presence of a two‐dimensional electron gas (2DEG), was observed in all samples below 80 K. The highest low temperature 2DEG mobility, 7500 cm2/V s, was measured in AlGaN/GaN grown on 6H–SiC; the sheet carrier density was 6×1012cm−2. Strong, well resolved, Shubnikov–de Haas oscillations were observed in fields as low as 3 T and persisted to temperatures as high as 15 K. Hall effect measurements also revealed the presence of well‐defined plateaus in the Hall resistance. The high quality 2DEG properties of the AlGaN/GaN heterostructures grown on 6H–SiC are attributed to the absence of significant parallel conduction paths in the material. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117096

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Picosecond photoinduced absorption measurements have been performed on four different (AlxGa1−x)0.5In0.5P fractal quantum well heterostructures. The results of these measurements reveal that, at early times following pulsed excitation, the carriers remain near the surface layer in which they were photogenerated, and populate the higher lying branches of theV‐shaped fractal structure. With increasing time, the carrier population relaxes toward the lowest energy, central wall. The rate at which the relaxation occurs is governed by the characteristic layer of widths of the fractal structure.

ISSN:0003-6951    

DOI:10.1063/1.117097

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Formation of epitaxial Si1−yCysubstitutional alloy layers on monocrystalline silicon surfaces withy≊1 at. % is reported. The preparation method was carbon ion implantation, followed by KrF excimer laser annealing. Results of Rutherford backscattering (RBS), secondary ion mass spectrometry (SIMS) and infrared absorption analyses are compared. The authors concluded that, up to ∼1 at. % carbon content, the dominant process is nonequilibrium trapping of carbon in substitutional lattice sites upon fast resolidification. Above this concentration the complex carbon redistribution processes are influenced by silicon carbide precipitation in the melt and segregation effects in the near‐surface region. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117098

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

Ion‐beam‐assisted deposition of Pt onp‐InP at room temperature was performed in order to produce Pt epitaxial films with high quality and Pt/p‐InP (100) heterostructures with sharp interfaces. From the x‐ray diffraction analysis, the grown film was found to be a Pt heteroepitaxial film. Auger electron spectroscopy measurements showed that the composition of the as‐grown film was Pt and that the interface quality between the Pt and the InP was relatively good. Transmission electron microscopy showed that the grown Pt was an epitaxial film. These results indicate that the Pt epitaxial films grown onp‐InP (100) can be used for both stable contacts in optoelectronic devices and Pt/InP metal‐semiconductor‐field‐effect transistors and that the Pt/InP heterostructures can give good motivation for the fabrication of Pt/InP superlattices. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117099

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The phase formation during rapid thermal annealing of a Ti/Mo bilayer sequentially deposited on Si substrates has been studied. The Mo layer varied from 0.5 to 2 nm and the Ti layer was always 60 nm thick. The presence of the Mo interposing layer enhances the formation of the C54 of TiSi2by first forming a Mo‐bearing silicide phase of hexagonal structure. The desired C54 phase then nucleates and grows on top of this Mo‐bearing silicide phase at a temperature as low as 650 °C via Si diffusion through the growing silicide layers. This is about 100 °C lower than what is usually needed for the C49–C54 transformation. The significance of this finding is that the usual route for the formation of TiSi2, i.e., the C49 phase forms as a result of the Ti–Si interaction and the C54 phase forms as the product of phase transformation, is altered by the interposition of a thin refractory metal (here Mo) layer between Ti and Si. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117100

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

An effective method for molecular beam epitaxial construction of metastable, pseudomorphic SnGe/Ge(001) heterostructures is presented. This method exploits a surfactant species, Bi, to alter Sn surface‐segregation kinetics. Using the x‐ray standing wave technique, we demonstrate not only that Bi segregates to the growth surface more strongly than Sn, but that it also dramatically suppresses the segregation mobility of Sn. The limited Sn diffusivity, which is believed to stem from the full coordination of subsurface Sn atoms, allows the epitaxy of well‐ordered, metastable SnGe heterostructures. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117101

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

We report molecular beam epitaxial growth of InAs on GaP(001), which has the largest lattice mismatch (11%) among all the arsenides and phosphides. Reflection high‐energy electron diffraction and high‐resolution transmission electron microscopy were used to optimize the growth and characterize the epilayer. It is found that the growth mode can be controlled by the surface V/III ratio: three‐dimensional and two‐dimensional layer‐by‐layer growths under As‐stable and In‐stable conditions, respectively. In both cases, a regular network of pure edge‐type (90°) misfit dislocations with a spacing of 4 nm was formed directly at the heterointerface, which corresponds to 85% of degree of strain relaxation. The epilayers grown under In‐stable conditions have relatively smooth surfaces with low threading dislocation densities. This is owing to the fact that the interface misfit dislocations were exclusively of the edge‐type which have no threading component and which relieve strain most effectively. The results demonstrate the ability to control the growth mode as well as the misfit dislocation nucleation type. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117102

出版商:AIP    

年代:1996

数据来源: AIP

摘要:

The optimum processing parameters for the fabrication of low‐loss waveguides in fused silica by ion implantation and annealing have been determined through a comparison of implantation‐induced physical and optical properties. The step height at an implanted/unimplanted boundary resulting from Si implantation was measured as a function of the ion dose (2×1012–6×1016/cm2) and energy (1–9 MeV) and the postimplantation annealing temperature (200–900 °C) and time (0.1–150 min). For a given ion energy (5 MeV), the step height increased for doses <∼1015/cm2and thereafter, saturated. For a given ion dose (2×1015/cm2), a near‐linear trend was evident for step height as a function of ion energy. Isochronal and isothermal annealing both resulted in a nonlinear reduction in step height, typical of a thermally induced process. In contrast to the continual reduction in step height observed during isochronal annealing, the loss coefficient exhibited a distinct minimum of ∼0.15 dB/cm at an intermediate temperature of 500 °C. This feature was consistent with the removal of a specific defect or color center. ©1996 American Institute of Physics.

ISSN:0003-6951    

DOI:10.1063/1.117103

出版商:AIP    

年代:1996

数据来源: AIP