Light scattering has been used to characterise the periodic surface topography which develops on (001) Si epitaxial layers growing by a step flow mechanism. The periodicity provides a measure of the average kink density along the misorientation steps which develop a sawtooth form during growth. The diffracting properties of the layers have been determined after growth by angle-resolved scattering measurements. In-situ light scattering at fixed angle has been used to fol low the build-up of the periodic step arrays. The periodic structure is a metastable state of the surface maintained by the supersaturation during growth, and it decays on switching off the silane source gas or when the temperature is reduced below the point at which surface diffusion will support the sawtooth step shape.

The first in-situ observations of initial stages of growth during Si vapour-phase homoepitaxy are reported, using the simultaneous measurement of dual-wavelength ellipsometry (364/488nm) and diffuse light scattering (488nm). Effective medium modelling shows that initial growth is nonuniform with pits present in the first 50–200Å of growth which rapidly fill in as growth proceeds. The sizes of the ellipsometric and scattering discontinuities are dependent on the extent of pre-growth roughening associated with oxide removal and finite wavelength effects become important for growth on roughened substrates.

The epitaxy of CaF2 on Si(111) is characterized on an atomic scale using various photoelectron spectroscopy techniques. We find both F and Ca bonding to Si with Ca forming most of the interface bonds. The bonding orbital is found at 1.5 eV below the valence band maximum of Si. It consists of the Si3p-like dangling bond orbital and the 4s electron of Ca1+. Ca has changed its oxidation state at the interface from Ca2+ to Ca1+, which is demonstrated by the multiplet structure of the Ca 2p absorption edge. The electronic properties of the CaF2 interface layer are altered dramatically relative to bulk material, with the band gap shrinking from 12 eV to about 2 eV. Such strong effects raise prospects for creating new materials in the vicinity of an interface.

The bonding at the interface between CaF2 and Si(111) has been investigated using core-level photoemission spectroscopy. The results are discussed in terms of various structural models of the interface. The stable interface has a depletion of fluorine from the interface resulting in strong Si - Ca bonding.

Core level spectroscopy measurements have been made on Si substrates with coverages of around one monolayer of As, Ga and GaAs. The interfaces were formed on on-axis Si(100) and Si(111) substrates using molecular beam epitaxy. Results are also presented for an arsenic monolayer on a single-domain Si(100) surface prepared by cutting the crystal off-axis by 4 degrees. The strong bonding between As monolayers and the surface of the substrate causes the GaAs to begin to form islands at average coverages of less than one monolayer. The surface between the islands is found to be terminated by a single atomic layer of As. Use of a Ga predeposition technique shows evidence of reducing the tendancy towards island formation.

We have used angular resolved ultraviolet photoemission spectroscopy to study the epitaxial growth of Si on GaP(110). Surface state emission obscures the top of the valence band (TVB). The Fermi level for the clean GaP(110) surface is 1.20±0.05eV above the TVB. 1ML (monolayer) of Si pins the Fermi level position at 1.40±0.05eV above the TVB. Further deposition of Si leads to a valence band discontinuity ΔEv=1.07 ±0.10eV.

Angular Resolved Photoemission Spectroscopy with Synchrotron radiation has been used to study the MBE growth of α-Sn on CdTe(110). Sn grows epitaxially and the Fermi level pins at 0.72eV above the CdTe valence band maximum. Outdiffusion or segregation of Cd in the α-Sn layer is not observed. For small Sn coverages the Sn4d core spectra show a second component which may be due to the initial interfacial growth of SnTe.

High-resolution photoemission spectroscopy was used to study the initial growth and interaction of In on Si(100). A quantification of the number of Si surface atoms selectively modified in the presence of an In adatom is enabled by decomposing the Si 2p core level into bulk and surface-shifted components; this analysis leads to an In-Si bonding coordination number determination. The In-to-Si bonding coordination number is 3 for very low In coverages and decreases to 2 for one half monolayer coverage. An analysis of the In 4d core levels indicates that the In adatoms occupy equivalent sites for the first 0.5 monolayers. Surface state emission near the top of the valence band persists for coverages exhibiting no Si 2p surface core level shift; implications regarding the different mechanisms I ehind the surface state and surface core level shift are addressed. The results are consistent with a structural model deduced from electron diffraction, Auger, and scanning electron microscopy studies.

We present electron diffraction, and high-resolution angle-resolved and angle-integrated photoemission studies of the initial phases of adsorption and growth of Ag on Ge(111). The results provide information on the structural properties of the Ge(111)-c(2×8) substrate surface, show Ag grows upon it almost laminarly at room temperature, and unambiguously demonstrate the presence of a small amount of Ge segregating on top of the growing Ag overlayer. The origins and behavior of these segregated atoms are discussed. Ag films more than a few monolayers thick exhibit quantum well states which are observed to evolve as a function of film thickness.

Electron scattering and diffraction in X-ray photoemission spectroscopy (XPS) have been used to characterize GaAs(001) and InP(001) chemically etched surfaces. 6a(3d),As(3d), In(4d) and P(2p) photoelectrons have been observed as a function of polar angles for the two [1–10] and [110] azimuths For kinetic energy range of these photoelectrons the experimental results have been correctly predicted by the single-scattering cluster model with spherical-wave corrections.

The problems of quantitative measurements in XPS have been discussed in relation with the diffraction phenomena.

High Resolution Electron Microscopy (HREM) images of the Al/InP interface were obtained from as-deposited films. The high purity Al films were deposited onto a clean (100) InP surface in a Molecular Beam Epitaxy (MBE) chamber. The in situ Reflection High Energy Electron Diffraction (RHEED) and Ultra-Violet Photoemission Spectroscopy (UPS) analyses showed a transformation of the InP surface during the Al deposition. The UPS data are interpreted as a strong exchange reaction between incoming Al and substrate In atoms. The In atoms are released and recover metallic behavior while Al atoms are involved in covalent bonds. At high coverages the RHEED analysis shows an epitaxial relationship in between Al and InP such as (110)Al//(100)InP with the two variants: [001]Al//[011]InP and [001]Al//[0–11]InP. The HREM images show that the interface AI/InP is perturbed and an intermediate layer is found. This layer appears to have the same crystal structure as InP indicated by extension of atomic planes from InP to the layer. However, the observed intensity, which corresponds to the mean potential of the forming atoms, is lighter than that of InP. Hence,out of these HREM and UPS results it is derived that an AlP or AlxIn1−xP compound is located at the Al/InP interface.

Organometallic vapor phase epitaxy (OMVPE) has achieved remarkable recent success, becoming the most promising technique for the ultimate production of III/V materials and device structures. Unfortunately, our understanding of the growth process remains primitive. In this paper we report a new technique for tracing the reactions by conducting the epitaxial growth in a D2 ambient using a time-of-flight mass spectrometer to analyze the product molecules. The pyrolysis reactions were studied for PH3, both alone and in the presence of trimethylindium (TMIn), and for TMIn alone and in the presence of PH3. For the reactants alone, the PH3 pyrolysis is completely heterogeneous at the InP surface, while TMIn pyrolyzes homogeneously in the gas phase. For TMIn and PH3 together, the reaction mechanism is entirely different; the pyrolysis temperatures for both PH3 and TMIn are lowered. Since the reaction produces only CH4 molecules, with a complete absence of CH3D at high ratios of PH3 to TMIn, we hypothesize that InP growth is initiated by the direct interaction of TMIn and PH3 molecules, either in the vapor phase at normal growth temperatures or at the InP surface at temperatures as low as 250°C.

We have applied kinetic simulation to MOCVD chemistry in a horizontal MOCVD reactor. Both chemical reactions and material diffusion are considered. For trimethylgallium decomposition, concentrations of chemical species reach their steady state values which differ largely from the equilibrium values.

Silicon vapor phase epitaxial growth with SiH2Cl2 is theoretically studied. The optimized geometries and total energigs of the species, generated from SiH2Cl2, are calculated by using ab initio molecular orbital method. As the intgraction between silicon surface and SiCl2 the charge transfer is considered. Based on the computational result that SiCl2 - has the lower total energy than SiCl2, a new adsorption mechanism, named, charge transfer adsorption, is p~oposed. By using this charge transfer adsorption followed by the surface reaction at the hollow bridge site, the epitaxial growths on the silicon (001), (111), and (110) surfaces are discussed.

Kinetics of epitaxial growth of GaAs from trimethylgallium (TMG) and arsine in organometallic chemical vapor deposition (OMCVD) have been suggested in the past to occur according to the Langmuir-Hinshelwood (L-H) or Langmuir-Rideal (L-R) mechanism [1–3], where competitive chemisorption of the Ga- and As-containing species is assumed. In contrast, formation of sp3 bonds on the GaAs growth front suggests that the Ga-containing species are less likely to chemisorb onto Assites, while the As-containing species are less likely to chemisorb onto Ga-sites. In addition, an analysis of probable chemical reactions and the unlikely event of homogeneous dissociation of hydrogen molecules indicate that the chemisorption of hydrogen must be included in the growth kinetics. Since H-As and H-Ga bonds have similar characteristics, such hydrogen chemisorption probably occurs on all sites. Thus, a mix of selective (Ga, As) and competitive (H2) chemisorption processes is likely to be present in practice. Furthermore, the presence of chemisorbed hydrogen will alter the surface As bonds, which, in the absence of hydrogen, are known to dehybridize and dimerize[4]. These basic issues have not been addressed in existing OMCVD growth models. Therefore, an analysis of the adsorption and growth processes, in the epitaxy of (100)GaAs is presented in this paper, with particular attention to the above issues.

Antiphase domain (APD) structures have been discovered in CdTe layers grown on (0001) sapphire substrates by MOCVD. To explain APD formation, an obstruction model based on a surface-reaction mechanism has been proposed. The proportion of one-phase domains to the total area varies with the [DETe]/[DMCd] ratio (VI/II ratio). A single-domain CdTe layer can be obtained at a VI/II ratio of 5. The APD structure shows a strong correlation with the crystallinity measured by X-ray. For a single-domain CdTe epilayer, theFWHM of the X-ray rocking curve shows 114 arc seconds and the EPD is 6×10 cm−2

High resolution electron microscope studies were undertaken of the epitaxy and oxidation of thin layers (<30Å) of vapor deposited Cu on single crystal Au films. The metal/metal and oxide/metal orientation relationships were analyzed for both the diffraction and imaging modes, before and after the Cu oxidation was significant. For the oxide overlayers two cases were studied: (111) Cu which transforms into three (110) variants of Cu2O, each rotated by 120° and (110) Cu transforming to a layered (211) oxide overgrowth. A lateral displacement of the surface top layer of Cu atoms was found for the (110) orientation of Cu2O. The (211) orientation of Cu2O had two structural variants of surface ordering rotated by 90° relative to the underlying metal. One of these cases directly exhibits a 3.01Å × 7.39Å supercell structure characteristic of a 0.58Å atomic step height of the (211) planar layers perpendicular to the surface.

The feasibility of studying dynamical changes in nickel thin films on ion-implanted silicon thin films by cross-sectional transmission electron microscopy (XTEM) with intermittent annealings in N2 ambient up to 850 °C is demonstrated. Interactions of nickel thin films with oxidation induced stacking faults, fluorine bubbles and process-induced defects in ion implanted silicon are provided as examples. The technique may be applied to clarify a number of important issues encountered in the study of the reactions and diffusion of thin films and obtain informations otherwise unattainable.

Using a planar thin-film specimen geometry, the growth kinetics of the spinel in NiOAl2O3 system has been studied with Rutherford backscattering spectroscopy. A thin-layer of Ni film is deposited by the electron-beam deposition technique onto single-crystal alumina substrates of different orientations including, (0001), {1120}, {1102} and {1100}. The subsequent heat-treatment in air then converts the Ni to NiO, thus producing a uniform layer of NiO with good adhesion between the NiO and the alumina. The kinetics of the Ni-Al spinel growth has been found to be different for different single-crystal substrate orientations. The kinetics behavior follows a parabolic growth-rate law for each orientation but shows a different reaction-rate constant. X-ray diffraction and transmission electron microscopy have been used as complementary techniques to confirm the phases that form at each stage of the heat treatment and the corresponding microstructures of the thin-film layers respectively.

The LPE grown AlxGa1−xSb was investigated by means of TEM, a carrier profiler and PL. The TEM image showed the dissociated 60° dislocations and Lomer-Cottrell sessile dislocation formed by the reaction of two dissociated 60° dislocations on different {111} planes. The EPMA measurement showed that Sb concentrations at the dislocation were lower than the stoichiometric composition. The epi-layer grown at 400°C had a relatively uniform carrier concentration of ∼7×1016cm−3. The PL spectra showed five emission peaks in 0≦×≦0.29. One shallow acceptor level and two native defect levels were introduced to interpret these PL emissions. The shallow acceptor level of Ev+∼30meV may be due to the defect of VGaGaSb. The native defects introduce two levels of EΓ1 - ∼90meV and EL1 - ∼160meV. The defect levels may be related to the complex defect of the Sb vacancy.