High quality single crystal films of AlxGa1−xN have been grown on sapphire substrates using low pressure metalorganic chemical vapor deposition at 915 °C over the entire range of x. Electrical and optical properties of the layers were measured. Electrical compensation by Be+ and N+ implants in the layers was studied. Schottky barriers were fabricated and their current voltage characteristics were studied. We also report some initial results of a study of GaN growth kinetics.

As an alternative disinfectant to chlorination, electrolytically generated copper:silver (400 and 40 micrograms/L copper and silver, respectively) with and without free chlorine (0.3 mg/L) was evaluated over a period of 4 weeks in indoor and outdoor water systems (100 L tap water with natural body flora and urine). Numbers of total coliform, pseudomonas, and staphylococci were all less than drinking water standards in systems treated with copper:silver and free chlorine and systems treated with free chlorine alone (1.0 mg/L). No significant differences (p less than or equal to 0.05) in bacterial numbers were observed between systems with copper:silver and free chlorine and those with free chlorine alone. Overall, free-chlorine treatments (0.3 or 1.0 mg/L) showed significantly lower heterotrophic plate numbers than those without free chlorine. When challenged with a natural Staphylococcus sp. isolate, water with copper:silver and free chlorine had a 2.4 log10 reduction in bacterial numbers within 2 min, while free chlorine alone or copper:silver alone showed 1.5 and 0.03 log10 reductions, respectively. Addition of copper:silver to water systems may allow the concentration of free chlorine to be reduced while still providing comparable sanitary quality of the water.

An n-p-n heterojunction structure, formed by the epitaxial growth of n-Ge on a p-GaAs substrate having a diffused n-GaAs region on the opposite face, has been employed to convert 1.5-μ radiation incident on the n-Ge face to 0.9-μ radiation emitted from the n-GaAs face. The internal quantum efficiency of the n-Ge, p-GaAs heterojunction is 0.62; the spectral response of the heterojunction is typical of photon effects in Ge. The internal wavelength conversion efficiency is 2.8×10−5, limited principally by the low electroluminescent quantum efficiency of the GaAs p-n junction at low injection current densities.

High quality single crystal GaN films with extremely uniform thicknesses have been grown in low pressure metalorganic chemical vapor deposition system using the reaction of (C2H5)3Ga with NH3. Electrical and optical properties of the layers were measured. Schottky barriers were fabricated after compensating the background donor concentration (typically ND ∼1×1019 cm−3) with Be+ or N+ implants. These Schottky barriers were electrically and optically characterized.

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