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Mechanism and growth rate of Metal-Induced-Lateral-Crystallization (MILC) with annealing temperature range from 550°C to 625°C were studied. Base on the MILC growth mechanism and effect of metal diffusion, a modeling on metal impurity distribution was developed. The modeling can be used to predict the distribution of metal impurity formed in the polysilicon layer after MILC annealing process. By applying the modeling, effects of annealing on the metal impurity distribution can be analyzed.

An A/B block copolymer consists of two macromolecules bonded together. In forming an equilibrium structure, such a material may separate into distinct phases, creating domains of component A and of component B. A dominant factor in the determination of the domain morphology is area-minimization of the intermaterial surface, subject to fixed volume fractions. Surfaces that satisfy this mathematical condition are said to have constant mean curvature. The geometry of such surfaces strongly influences material physical properties. We have discovered domain structures in microphase-separated diblock copolymers that closely approximate periodic surfaces of constant mean curvature. Transmission electron microscopy and computer-simulation are used to deduce the three dimensional microstructure by comparison of tilt series with two-dimensional image projection simulations of three-dimensional mathematical models. Two structures are discussed: First is the double diamond microdomain morphology, associated with a newly discovered family of triply periodic constant mean curvature surfaces. Second, a doubly periodic boundary between lamellar microdomains, corresponding to a classically known minimal surface (Scherk’s First Surface), is described.

Several multilayer test coatings for hard X-ray telescopes were fabricated using DC magnetron sputtering. The process parameters were selected from a series of trials of single layer depositions. The samples were characterized using X-ray specular reflectivity scans, AFM, and cross-sectional TEM. Additional measurements (stylus profilometry, RBS, and Auger analysis) were used in the optimization of the deposition rate and of the thin film properties (density, composition, surface/interface microroughness). The X-ray reflectivity scans showed that the combinations of reflector and spacer materials tested so far (W/Si and W/C) are suited for graded d-spacing multilayer coatings that present a constant reflectivity bandpass up to 70 keV.

This paper presents the development of low dark current amorphous silicon (a-Si:H) based heterojunction photodiodes. A series of p-i-n and n-i-p structures have been deposited by plasma-enhanced chemical vapor deposition (PECVD). Junction properties and carrier transport are investigated in terms of dark and light current-voltage characteristics, time dependence of the dark current, and spectral photoresponse measurements. It is demonstrated that a thin (∼4 nm) undoped a-SiC:H buffer layer introduced between the p and i layers reduces the leakage current and improves the diode ideality factor. A dark current density of ∼10 pA/cm2 at reverse bias of 1 V was achieved for the n-i-p structure. Optimization of device design for further improvement of dark current and photoresponse is discussed.

We have investigated the molecular beam epitaxial growth of homoepitaxial InAs and GaSb and InAs/GaSb heterostructures on both the (111)A and (111)B orientations. Our studies have found that high quality GaSb epilayers can be grown on both the (111)A and (111l)B orientations over a wide range of growth temperatures and flux ratios. Reflection high energy electron diffr-action phase diagrams for GaSb [111[ are presented. InAs/GaSb heterostructures, simultaneously grown on (11l)A and (111)B orientations, have been investigated by secondary ion mass spectroscopy depth profiles and double crystal x-ray diffraction. Unintentional incorporation of the ‘second’ group-V element is found to be approximately three times greater in the (111)A orientation than in the (111)B for both species.

The new generation of high energy accelerators - LHC, CEBAF, RHIC - have encouraged the development of more robust plastic scintillators. Monitors and detectors for these machines will require plastic scintillator with greater radiation tolerance. Although the major cause of radiation damage in plastic scintillator is the creation of color centers in the base plastic, the most successful approach to date has been to utilize fluors which circumvent, rather than solve, the radiation damage problem. Two techniques have been found to be useful. First, increase the concentration of fluors so that the optical density of the fluors for absorption of the scintillation photons remains much higher than the optical density of the radiation induced color centers. Second, use fluors which emit at longer wavelengths than traditional fluors, thus avoiding radiation induced color centers. The present work attempts to meet these requirements by modifying the structure of the 3-HF molecule.

Magnetization, TEM, and x-ray diffraction studies have been carried out on GdCox films sputtered onto Si or sapphire substrates at ~90 C, ambient temperature. The composition range studied was x=2−8.5. Over the composition range defined approximately by 5>×>3, the films, which are 1–3 microns thick, exhibit a unidirectionally displaced B-H loop, characteristic of an exchange-biased phase. TEM studies indicated that the samples with the shifted loops indeed consist of a mixture of amorphous and microcrystalline phases. The characteristic size of the microstructure is 10–20 A. Electron diffraction shows a very broad ring characteristic of amorphous phase together with six or seven sharper rings characteristic of crystalline material which index best to the hexagonal GdCo5 structure or to a high temperature hexagonal Gd2Co17 phase. The diffraction pattern remains virtually unchanged over the composition range x=2–8. This leads us to conclude that the microcrystalline material consists of one, or perhaps more than one, metastable phase over the indicated composition range. X-ray diffraction shows only one broad maximum.

The effects of chemical etching, mechanical thinning, and ion milling on the low temperature photoluminescence spectra of MBE grown (001) CdTe films are reported. Line defects observed by TEM are correlated with photoluminescence. It is shown that X-ray D.C.R.C, measurements in these films are weighted averages over the whole thickness of the films and therefore weakly reflect the structural perfection of the samples near the surface as deduced by photoluminescence.