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We describe a highly sensitive new type of calorimeter based on the deflection of a ‘‘bimetallic’’ micromechanical sensor as a function of temperature. The temperature changes can be due to ambient changes, giving a temperature sensor or, more importantly, due to the heat absorbed by a coating on the sensor, giving a heat sensor. As an example we show the results of using the sensor as a photothermal spectrometer. The small dimensions and low thermal mass of the sensor make it highly sensitive and we demonstrate a sensitivity of roughly 100 pW. By applying a simple model of the system the ultimate sensitivity is expected to be of the order of 10 pW. The thermal response time of the cantilever can also be determined, giving an estimate of the minimum detectable energy of the sensor. This we find to be 150 fJ and again from our model, expect a minimum value of the order of 20 fJ.

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Using a modified atomic force microscope (AFM) with a conducting cantilever, we have investigated the dielectric strength of SiO2 gate oxide films. This has been achieved by spatially resolving the prebreakdown tunneling current flowing between the silicon substrate and tip. During AFM imaging a voltage ramp was applied to the tip at each image point so as to determine the local threshold voltage required to generate a small tunneling current in the oxide, without causing an irreversible electrical breakdown. For an oxide 12-nm thick this voltage was found to vary by more than a factor of 2.7 over an area of 0.14 μm2, with a maximum value of 40.5 V. This suggests that the breakdown strength of conventional metal-oxide-silicon capacitors may not be limited by the intrinsic dielectric strength of the oxide, but by imperfections or nonuniformities in the Si/SiO2 structure. By preventing irreversible oxide breakdown during scanning, we can image the dielectric properties of oxide films with a lateral resolution better than 20 nm.

The electron field-emission process for nitrogenated amorphous carbon ͑a-C:H:N͒ thin films deposited using a magnetically confined hydrocarbon plasma is examined. The morphology of the films obtained using an atomic force microscope is compared to the field-emission properties. Beyond a chemical composition of 14 at. % nitrogen, the mirror smooth a-C:H:N films become self-texturing, and multiple ''domelike'' cathodes of nanometer scale are observed. The dimensions of these ''domelike'' cathodes varies with time, and after a 15 min deposition have dimensions of approximately 50 nm base diameter and 20 nm in height. When the electronic field emission of these textured films ͑N content 15 at. %͒ are measured, there is an enhancement in the emitted current density of ϳ2 orders of magnitude at an electric field of 20 V/ m, in comparison to the untextured films with a nitrogen content of 11 at. %.