Quality Si thin films were grown by the metal-induced growth (MIG) method. Metal (Co, Ni, or mixing of Co and Ni) was thermally evaporated on a 200 nm-SiO2 coated Si wafer. Si sputtering was performed at 600 – 620 °C in a dc magnetron system. The reaction of Si and metal first formed a silicide (CoSi2 or NiSi2) layer and further Si sputtering grew a Si film above it. The grown Si films were practically fabricated for Schottky photodiodes and electrically measured under one sun scan illumination (100 mW/cm2).

We employed the postgrowth impurity-free vacancy diffusion technique to selectively tune the bandgap of the InAs/InGaAlAs dots-in-well laser structure grown on (100) InP substrate. A blueshift up to 170 nm with a significant decrease in the photoluminescence linewidth has been observed. Spatial control of the bandgap shifts has been achieved using SiO2 and SixNy layers as annealing caps. A differential wavelength shift of 76 nm has been observed after a rapid thermal annealing step at 750 °C for 30 s. In contrast to most reported results in other material systems using similar process, we observed a larger bandgap shift from the SixNy capped samples than from the SiO2 capped samples. Our theoretical calculation indicates that the unusual intermixing behavior in this material system is governed by different interdiffusion rates of group-III atoms.

Beginning in 1952, waste materials, including volatile organic compounds (VOCs)contaminated with transuranic radionuclides, were generated during the fabrication, assembly, and processing of nuclear weapons components in the US Department of Energy (DOE) weapons productions complex at the Rocky Flats Plant (RFP). Following processing and containerization, drums were shipped to the Subsurface Disposal Area (SDA) at the Idaho National Engineering and Environmental Laboratory (INEEL). During 1968 approximately 9,691 drums were buried there.

In subsequent years, observations made during drum retrieval studies indicated that many of the drums were compromised on impact or suffered physical damage by compaction equipment shortly after burial. Corrosion also appears significant on drums buried for a few years. A large vadose-zone contaminant plume composed of solvents buried in the drums has been found beneath the burial area.

Phase partitioning calculations show it unlikely that separate-phase solvent has leaked from the compromised drums deep into the soil profile or that solvents have dissolved into infiltrating water. Rather, it appears that the solvents are evaporating out of the barrels into the air phase and further partitioning from there throughout the subsurface.

This paper describes the history of mixed wastes buried at the SDA, phase partitioning, and preliminary computer simulation results on gas contaminant mobility in the vadose zone.

Low temperature (LT) processed ZnSe MSM photodetectors can be used for detecting Gamma rays or X-rays using scintillation crystals in many space and medical applications. Metalsemiconductor-metal (MSM) photodetectors were fabricated on undoped ZnSe grown by molecular beam epitaxy (MBE) on semi-insulating (100) GaAs substrates. The MSM photodetectors consist of interdigitated metal fingers with 2 μm, 3 μm, and 4 μm spacing on one chip. Probimide and SiO2 thin films were deposited to aid the LT lift-off process before the pattern generation. An interdigitated structure was achieved by photolithography and reactive ion etching. Pd Schottky metal was deposited at a substrate temperature near 77 K using a lift-off technique. The LT metallization provides an improved interface between metal and semiconductor interface. Continuous wave signal to noise ratio (SNR) of 1.57×104 was obtained for 2 μm interdigitated photodetectors, operated under 180 nW optical power at a wavelength of 400 nm. The detectors showed good DC saturation characteristics indicating a low surface recombination. Saturation current without illumination remained at around less than 1 pA for a ± 10 V biasing. Detectors exhibited linearity with light intensity and DC bias voltage suggesting no gain mechanism involved, and showed a high spectral responsivity (0.6 (A/W)) at a wavelength of 450 nm at 5V applied bias.