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 open-circuit voltage decay (OCVD) method is a well-known technique for conducting electrical measurements of carrier lifetime: the main advantages lie in the simple setup and the possibility of carrying out measurements in commercial devices without the need of removing the package, as for optical methods. Despite several researchers having reported carrier lifetimes measured by the OCVD method in different devices, there has been little discussion about the potential effect of the experimental setup on the obtained results. By comparing the outputs of the experimental measurements with those of numerical simulations, this study investigates the overlooked effect of the OCVD measurement setup on the former. Due to the growing importance of SiC-based devices, the analysis is applied to a 4H-SiC p-i-n diode. Two main points are addressed: 1) the effect of circuit setup on the ambipolar lifetime is discussed and a method, originally developed for improving the estimate of low-level carrier lifetime in OCVD measurements, is used to correct the measured lifetime for this influence; 2) the origin of the local minimum eventually appearing in the lifetime versus time curves is also investigated. It is found that the minimum can also be related to the time constant of the experimental setup, giving rise to doubts about the usual interpretation of this minimum as the minority carrier lifetime. A method is thus proposed to help discriminate between the two interpretations.

Silicon carbide (SiC) is an interesting semiconductor for MEMS devices. The high-value Young’s modulus of silicon carbide facilitates high frequencies and quality (Q) factors in resonant devices built with double-clamped beams. The aim of this work is to achieve the determination and modeling of the Q-Factor for samples of micromachined 3C-SiC film on silicon substrates. This study demonstrates that the experimental datasets created by Romero, integrated with the thicker samples reported in this work, fit the theoretical model presented in the paper. Furthermore, the influence of the crystallographic defects present at the 3C-SiC/Si interface on the Q-factor can be observed both in the analytical model of Romero and in the numerical model present in COMSOL. 3C-SiC layers with thickness greater than 600 nm are needed to achieve an ideal performance from double-clamped beams.

The study focuses on analysing the high-level carrier lifetime (τ _HL ) in 4H silicon carbide (4H-SiC) PiN diodes under varying temperatures and proton implantation doses. The objective is to identify an empirical law applicable in technology computer-aided design (TCAD) modelling for SiC devices, describing the dependence of carrier lifetime on temperature to gain insights into how irradiation dose may influence the τ _HL . We electrically characterize diodes of different diameters subjected to different proton irradiation doses and examine the variations in current-voltage (I-V) and ideality factor (n) curves under various irradiation conditions. The effects of proton irradiation on the epitaxial layer are analysed through capacitance-voltage (C-V) measurements. We correlate the observed effects on I-V, n, and C-V curves to the hypothesis of formation of acceptor-type defects related to carbon vacancies, specifically the Z _1/2 defects generated during the irradiation process. The impact of irradiation on carrier lifetime is investigated by measuring τ _HL using the open circuit voltage decay (OCVD) technique at different temperatures on diodes exposed to various H ⁺ irradiation doses with constant ion energy. This investigation reveals the presence of a proportional relationship between 1/τ _HL and the dose of irradiated protons: the proportionality coefficient, referred to as the damage coefficient (K _T ), exhibits an Arrhenius-type dependence on temperature. OCVD-measured lifetime on the various diodes demonstrates a power-law dependence of lifetime on temperature. The exponent of this dependence varies with the irradiation dose, notably showing an increase in temperature dependence at the highest H ⁺ ion dose. This suggests a threshold-like dependence on H+ irradiation dose in the τ _HL -temperature relationship.

In this work, we investigate the correlation between tensile residual stress and Q-factor of double-clamped beams fabricated on epitaxial 3C-SiC layers grown on both and silicon substrates, using a completely optical measurement setup to measure the Q-factor of the resonators and the residual stress of the layers by means of purposely designed micromachined test structures. From the measurements, a clear correlation appears between the residual stress of the SiC layer and the Q-factor of the resonators, with Q-factor values above half a million for resonators fabricated on substrates, showing residual stress around 1 GPa.

Silicon carbide (SiC) has emerged as a highly attractive material for microelectromechanical systems (MEMS) operating in harsh environments, owing to its outstanding mechanical, thermal, and chemical properties. This review provides a comprehensive overview of the advantages and limitations of SiC-based MEMS, with particular emphasis on the strong interdependence between material structure, mechanical properties, and epitaxial growth processes. The role of defects, residual stress, and crystal quality is discussed in relation to device performance and reliability. Special attention is devoted to cubic SiC grown on silicon substrates, highlighting how growth-induced features influence the mechanical response of micromachined structures. Furthermore, a detailed analysis of the quality factor (Q-factor) is presented for 3C-SiC (111)/Si resonators, including the development of analytical models and their validation through numerical simulations performed using COMSOL Multiphysics (Version 6.1). The necessity of incorporating anisotropic loss factors in numerical modeling is demonstrated to be essential for accurately describing the experimentally observed behavior. This review aims to provide design guidelines and modeling strategies for the optimization of SiC MEMS, supporting their further development for high-performance and extreme-environment applications, including pressure sensors, mechanical resonators and high-stress-tolerant sensors.