This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.sna.2016.01.00

3C-SiC is an emerging material for MEMS systems thanks to its outstanding mechanical properties (high Young’s modulus and low density) that allow the device to be operated for a given geometry at higher frequency. The mechanical properties of this material depend strongly on the material quality, the defect density, and the stress. For this reason, the use of SiC in Si-based microelectromechanical system (MEMS) fabrication techniques has been very limited. In this work, the complete characterization of Young’s modulus and residual stress of monocrystalline 3C-SiC layers with different doping types grown on and oriented silicon substrates is reported, using a combination of resonance frequency of double clamped beams and strain gauge. In this way, both the residual stress and the residual strain can be measured independently, and Young’s modulus can be obtained by Hooke’s law. From these measurements, it has been observed that Young’s modulus depends on the thickness of the layer, the orientation, the doping, and the stress. Very good values of Young’s modulus were obtained in this work, even for very thin layers (thinner than 1 μm), and this can give the opportunity to realize very sensitive strain sensors.

The processing parameters which favour the onset of an impurity band conduction around room temperature with a contemporaneous elevated p-type conductivity in Al⁺ implanted 4H-SiC are highlighted by comparing original and literature results. In the examined cases, Al is implanted at 300–400 °C, in concentrations from below to above the Al solubility limit in 4H-SiC (2 × 10²⁰cm⁻³) and post implantation annealing temperature is ≥1950 °C. Transport measurements feature the onset of an impurity band conduction, appearing at increasing temperature for increasing Al implant dose, until this transport mechanism is enabled around room temperature. This condition appears suitable to guarantee a thermal stability of the electrical properties. In this study, the heaviest doped and less resistive samples (Al implanted concentration of 5 × 10²⁰cm⁻³ and resistivity of about 2 × 10⁻² Ω cm) show a carrier density above the Al solubility limit, which is consistent with at least a 50% electrical activation for a 15% compensation. The model of Miller and Abrahams well describes the resistivity data of the lower doped sample, whereas a deviation from the behaviour predicted by such a model is observed in the higher doped specimens, consistent with the occurrence of a variable range hopping at low temperature.