Metal silicides have played an indispensable role in the rapid developments of microelectronics since PtSi was first used to improve the rectifying characteristics of diodes in early 1960s. This wo ...

Metal silicides in CMOS technology : Past, present, and future trends

Nanoscale radiation heat transfer for silicon at different doping levels

In this paper we present a vertical-cavity enhanced resonant thermal emitter---a highly directional, narrow-band, tunable, partially coherent thermal source. This device enhances thermal emittance of a metallic or any other highly reflective structure to unity near a cavity resonant frequency. The structure consists of a planar metallic surface (e.g., silver, tungsten), a dielectric layer on top of the metal that forms a vertical cavity, followed by a multilayer dielectric stack acting as a partially transparent cavity mirror. The resonant frequency can easily be tuned by changing the cavity thickness (thus shifting resonant emission peak), while the angle at which the maximum emittance appears can be tuned as well by changing the number of dielectric stack layers. The thermal emission exhibits an extremely narrow angular emission lobe, suggesting increased spatial coherence. Furthermore, we show that we can enhance the thermal emission of an arbitrarily low-emittance material, choosing a properly designed thermal cavity, to near unity.

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Resonant-cavity enhanced thermal emission

The Starshot Breakthrough Initiative established in 2016 sets an audacious goal of sending a spacecraft beyond our Solar System to a neighbouring star within the next half-century. Its vision for an ultralight spacecraft that can be accelerated by laser radiation pressure from an Earth-based source to ~20% of the speed of light demands the use of materials with extreme properties. Here we examine stringent criteria for the lightsail design and discuss fundamental materials challenges. We predict that major research advances in photonic design and materials science will enable us to define the pathways needed to realize laser-driven lightsails.

Materials challenges for the Starshot lightsail

This article presents calibration techniques for heated silicon atomic force microscope cantilevers and analyzes the accuracy of these techniques. A calibration methodology using Raman thermometry is presented and validated with heat transfer simulations and experimental measurements. Raman thermometry generates a calibration standard against which other techniques can be compared. Theoretical predictions of the cantilever temperature-dependent electrical properties do not by themselves provide accurate cantilever temperature calibration. Isothermal calibration is also insufficient. The temperature calibrations are stable with storage time and number of heating cycles, although an electrical ‘burn-in’ period is required to stabilize the cantilever response. These techniques for precise temperature calibration of heatable silicon cantilevers are required for applications where temperature must be carefully controlled, including surface science measurements and nano-manufacturing.

Temperature calibration of heated silicon atomic force microscope cantilevers

The temperature dependences of the spectral and total hemispherical emissivities of silicon have been experimentally determined, by using a technique which combines isothermal electron beam heating with in situ optical measurements. Emission spectra were used to deduce the absorption coefficient for phosphorus‐doped silicon samples for wavelengths between 1.1 and 1.6 μm, in the temperature range from 330 to 800 °C. For lightly doped samples, the data show good agreement with a model which includes the effects of the various phonon‐assisted processes involved in interband transitions in silicon, as well as the free‐carrier absorption. For heavily doped samples the agreement was less satisfactory, possibly because of inadequacies in the model for free‐carrier absorption. It was shown that reflection spectra can also be used to determine the absorption spectrum, for the range where the absorption coefficient lies between 1 and ∼70 cm−1. By fitting the theoretical model to the absorption coefficients derived ...

P. J. Timans

Papers

Emissivity of silicon at elevated temperatures