We report the simultaneous monitoring of the environment-state and wafer-state during epitaxial crystal growth using a single real-time measurement. Atomic absorption spectroscopy (AAS) is used to monitor the incident molecular beam flux while UV reflectance (UVR) at 396 nm with an incident angle of 78° is used to monitor growth on the wafer. We have studied the utility of AAS/UVR monitoring of AlxGa1-xAs deposition: AlAs growing on GaAs, GaAs on AlAs, and superlattice growth. Additionally, optical multichannel spectroscopy (OMS) data were acquired throughout the growth of a distributed Bragg reflector (DBR). The relationship of the structure of the real-time OMS data to absorption, optical path length variation, and differential layer thickness variations is also discussed. Numerical simulations of the real-time wafer-state monitors using pseudodielectric constants, appropriate at a growth temperature of 579 °C, show good agreement with measured spectra.

In many situations where islands and quantum dots are formed on a growing surface strain effects are believed to play an important role. Here we present some preliminary results from a computer simulation study of a one-dimensional model system. Our system consists of an A material upon which grows a B material with a different lattice constant. We only consider the case where less than one monolayer of B has grown on the surface. At any given time the surface consists of a series of “islands” of B bounded by up and downsteps. Dispersed between these islands are mobile B atoms. In general, because of the lattice mismatch between A and B the mobile B atoms are repelled from the islands. This repulsion has an effect on the island size distribution and more particularly on the number of islands per unit length. Here we show that for a moderate repulsion there is a large effect on the number of islands per unit length. However, as the repulsion is increased the effect grows only gradually.

This work demonstrates the successful application of the precision cross-sectioning technique to the characterization of two types of Si-based nanostructures. Careful wedge-polishing of an array of metal-coated poly-Si microlines gave electron transparency over areas as broad as 1.5 mm across. A single, specific, SET (Single Electron Transistor), having dimensions of 4 × 4 μm2, was cross-sectioned for examination using conventional and high-resolution TEM imaging.

Hard X-ray microprobes from synchrotron radiation ( SR ) sources should be powerful tools for various fields of research. A Fresnel zone plate ( FZP ) is a promising focusing element for X-ray. In order to develop high performance multilayer FZP for use in hard X-ray region, Ag/C and Cu/Al concentric multilayers were prepared by some deposition parameters. A dependence of the zone boundary structures on the Ar gas pressure was observed: the multilayer prepared at lower Ar gas pressure had smoother zones. Substrate cooling did not improve the zone boundary structures. From the focusing test of the Cu/Al FZP by the SR, a microbeam of 1.3 μ m ø has been obtained for 8 KeV X-ray (λ =0.154nm).