Well aligned multiwalled carbon nanotube (CNT) growth was achieved by positively biasing the substrate during growth. Growth was performed in a flowing mixture of 7% CH4 in Ar onto Co covered Si held at 800 °C with and without the presence of an electric field. High resolution scanning electron microscopy shows that the tube alignment occurs only when a positive bias is applied to the substrate whereas no aligned growth occurs under a negative bias and no tube growth is observed, under the presently applied conditions, with no field. This finding may open up the possibility of realizing cold electron emitting devices based on CNTs with a large electric field enhancement. In particular, it may be possible to utilize the same gate which is needed to turn the device on also to obtain field assisted aligned carbon nanotube growth into the desired regions. Alternatively, due to the fact that no CNTs grow under the conditions of this experiment without bias, selected area biasing may permit selected area growth of vertically aligned carbon nanotubes, a process that may find many applications.

Absolute quantum photoyield (QPY) measurements (140–210 nm) of chemical vapor deposited (CVD) diamond films are reported. The dependence of the QPY on hydrogenation by exposure to a hydrogen microwave (MW) plasma and oxidation by a mixture of acids or on exposure to air under ambient conditions have been studied. Films deposited by MWCVD display a higher QPY than those grown by hot filament (HF) CVD. The QPY values are found to depend on the state of the surface. Hydrogen-terminated films exhibit values above 12% at 140 nm, whereas even small amounts of oxygen strongly degrade the QPY. B-doping, at the level of 1500 ppm, has no apparent effect on the photoemission properties. Exposure of the hydrogenated films to ambient conditions results in oxygen adsorption, leading to degradation of the photoemission properties. Analysis of the data within the three-step model of photoemission clearly shows that the state of the surface is a dominant factor determining the QPY.

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