Electrical properties of strained nano-thin 3C–SiC/Si heterostructures

Abstract

The effects of strain on the conduction mechanism in heterostructures consisting of strained nano-thin 3C–SiC films on Si are reported. These films exhibit significantly different electrical behaviours than the bulk material. Strained nano-thin 3C–SiC films were grown on n-type Si substrates by gas source molecular beam epitaxy. Reflection high-energy electron diffraction patterns show that these films are about 3% strained relative to the SiC lattice constant. In order to investigate the electrical properties of thin film structures, Al, Cr and Pt contacts to a nano-thin film 3C–SiC were deposited and characterized. The I–V measurements of the strained nano-thin films demonstrate back-to-back Schottky diode characteristics and the band offsets due to the biaxial tensile strain introduced within the 3C–SiC films were calculated and simulated. Based on the experimental and simulation results, an empirical model for the current transport in the heterostructures based on strained nano-thin films has been proposed. It was found that due to the band alignment of this structure, current is constrained at the surface which allows use of nano-thin films as surface sensors.

Photoresponse of a Highly-Rectifying 3C-SiC/Si Heterostructure Under UV and Visible Illuminations

“…By taking the advantages of silicon-orientated mature MEMS processing technologies, 3C-SiC on the Si structure has opened a new platform to develop a wide range of better and low cost highly sensitive physical sensors for harsh environments. Although the best efforts have been made to grow high quality 3C-SiC film on Si-substrate, the grown 3C-SiC/Si heterojunction experiences crystal defects and film stress at the interfaces due to different thermal expansion coefficients and the lattice mismatch between 3C-SiC and Si [9], [10]. The crystal defects, mainly stacking faults, as well as film quality can be improved by carbonizing the active silicon surface before the deposition of 3C-SiC [10], [11].…”

Electrical leakage phenomenon in heteroepitaxial cubic silicon carbide on silicon

“…For completeness, we note that an additional potential reason for the degradation of the SiC/Si junction could be the reduced band gap arising from the residual tensile strain in the SiC epilayers. 9 That is, the band gap reduction results in a smaller valence band barrier and leads to increased hole current injection from the Si to the SiC. 9 To test the hypothesis of tensile strain-induced SiC band gap changes on the junction we simulated the SiC/Si system with the strained band gap and electron affinity values mentioned by Rahimi et al 9 and found that even a large concentration of those acceptor traps (up to ~10 20 cm -3 ) in the film does not appreciably contribute to the degradation of the heterojunction between the SiC film and the substrate.…”

“…2 Moreover, studies of strained heterostructures have shown that the substantial tensile strain generated from the lattice and thermal expansion coefficient mismatch between 3C-SiC and silicon may reduce the band gap of the SiC. 9 Nevertheless, a detailed explanation of the leakage/shorting phenomenon, and the impact of this challenge on the electrical properties of 3C-SiC layers are poorly documented in the literature.…”

Properties and Applications of Ceramic Composites Containing Silicon Carbide Whiskers

“…However, it has also been proposed that matrixSiC w stress transfer can explain observations of (tensile) whisker fracture instead of pullout: specifically, that the higher-modulus SiC whiskers unload the matrix and reduce stress around defects in the composite microstructure and result in an overall improvement in composite mechanical properties (Björk & Hermansson, 1989). The mechanical stress distribution within the SiC whiskers might also affect electrical response of composites because elastic strain was found to result in changes in electrical response of -SiC films and used to explain the observed back-to-back Schottky-barrier response (Rahimi et al, 2009). …”