A model for laser melting of carbon at high temperatures to form liquid carbon has been developed. This model is solved numerically using experimental data from laser irradiation studies in graphite consistent with a melting temperature for graphite of 4300 K. The parameters for high-temperature graphite are based on the extension of previously measured thermal properties into the high-temperature regime. A simple classical free electron gas model is used to calculate the properties of liquid carbon. There is very good agreement between the model calculation and experimental results for laser pulse fluences below 2.0 J/cm2. Modifications to the model for larger laser pulse fluences are discussed.

Nonvolatile, electric-pulse-induced resistance switching is reported on S and Co doped ZnO thin films deposited on different substrates using magnetron sputtering and laser ablation. Two resistance states were obtained by applying voltage pulses of different polarity. The switching was observed regardless of the substrate, dopant species, or microstructure of the samples. In the Co doped ZnO samples, the two resistance states are remarkably stable and uniform.

Braunstein, G.; Muraviev, A.; Saxena, H.; Dhere, N.; Richter, V.; and Kalish, R., "p type doping of zinc oxide by arsenic ion implantation" (

Proton exchanged samples of LiNbO, have been profiled by micro-Raman spectroscopy, secondary ion mass spectroscopy, Rutherford backscattering channeling, and by x-ray diffraction (XRD). Following proton exchange (PE) there are two different phases in addition to pure LiNbO, detected by XRD. After successive annealing steps the outermost phase disappears and an interfacial region forms progressively between PE and LiNbO,. Specific vibrational bands are correlated to electro-optic and nonlinear optical properties of the system, and the recovery of these properties upon amrealing is correlated to chemical bonding changes.

The electrical conductivity of Na- and Li-implanted diamond is investigated. The highest conductivities are obtained for high dose implantations followed by thermal graphitization of the heavily damaged layer and chemical removal of the graphitized layer. The temperature dependence of the resistivity is measured, yielding activation energies of 0.2 eV for Li (400<T<680 K) and for Na 0.13 eV (220<T<400 K) and 0.21 eV (415<T<670 K). Analysis of the data shows that the conduction may be understood in terms of variable range hopping between implant sites in the crystal rather than due to thermal activation.

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Highly conducting p-type diamond layers have been obtained by high-dose boron implantation followed by annealing (1400 °C) and subsequent removal of the graphite-like layer that is formed as a result of the heat treatment. Conductivity and Hall measurements showed transport features typical of heavily doped semiconductors. The fact that identical carbon implantations have yielded no measurable conductivity is taken as evidence that the highly conductive p-type layer obtained by boron implantation is indeed due to effective doping.

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