Electrical properties of strained nano-thin 3C–SiC/Si heterostructures (original) (raw)
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Novel Electrical Characterization of Thin 3C-SiC Films on Si Substrates
Science of Advanced Materials, 2014
Thin semiconductor films provide many functional uses in the fields of electronics, sensors, optics, and microelectro-mechanical systems (MEMS). A prime example is the case of thin film 3C-Silicon Carbide epitaxially grown on standard silicon wafers. The required SiC layer thickness for these applications ranges from a few nanometers to a few microns, and process conditions that control film stress, doping type and concentration, crystal orientation, and surface roughness need to be developed along with accurate physical and electrical characterization techniques. In this paper, we present two novel variations on established measurement techniques. Firstly, the hotprobe technique is used as a simple, non-destructive method to monitor film doping and crystal quality based on the open circuit voltage and short circuit currents. Results are presented for both ntype and p-type films grown on and silicon orientations, and supported by transmission electron micrographs and X-ray diffraction data. Secondly, a technique based on the four point resistivity measurement is used to determine film resistivity while eliminating the errors introduced by substrate leakage.
Nanoscale characterization of electrical transport at metal/3C-SiC interfaces
Nanoscale Research Letters, 2011
In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (Φ B ) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt 2 Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis.
3C-SiC HeteroEpitaxial Films for Sensors Fabrication
Advances in Science and Technology, 2008
Silicon Carbide (SiC) is a very promising material for the fabrication of a new category of sensors and devices, to be used in very hostile environments (high temperature, corrosive ambient, presence of radiation, etc.). The fabrication of SiC MEMS-based sensors requires new processes able to realize microstructures on bulk material or on the SiC surface. The hetero-epitaxial growth of 3C-SiC on silicon substrates allows one to overcome the traditional limitations of SiC microfabrication. This approach puts together the standard silicon bulk microfabrication methodologies with the robust mechanical properties of 3C-SiC. Using this approach we were able to fabricate SiC cantilevers for a new class of pressure sensor. The geometries studied were selected in order to study the internal residual stress of the SiC film. X-Ray Diffraction polar figure and Bragg-Brentano scan analysis were used to check to crystal structure and the orientations of the film. SEM analysis was performed to analyze the morphology of the released MEMS structures.
Journal of The Electrochemical Society, 2010
Chemical vapor deposition in the low pressure regime of a high quality 3C-SiC film on silicon ͑100͒-oriented substrates was carried out using silane ͑SiH 4 ͒, propane ͑C 3 H 8 ͒, and hydrogen ͑H 2 ͒ as the silicon supply, carbon supply, and gas carrier, respectively. The resulting bow in the freestanding cantilever structures was evaluated by an optical profilometer, and the residual gradient stress ͑ 1 ͒ in the films was calculated to be approximately between 15 and 20 MPa, which is significantly lower than the previously reported 3C-SiC on Si films. Finite element simulations of the stress field in the cantilever have been carried out to separate the uniform contribution ͑ 0 ͒, related to the SiC/Si interface, from the gradient one ͑ 1 ͒, related to the defects present in the SiC epilayer.
Residual Stress Measurement on HeteroEpitaxial 3C-SiC Films
Materials Science Forum, 2009
The fabrication of SiC MEMS-based sensors requires new processes able to realize microstructures on bulk material or on the SiC surface. The hetero-epitaxial growth of 3C-SiC on silicon substrates allows one to overcome the traditional limitations of SiC micro-fabrication. This approach puts together the standard silicon bulk microfabrication methodologies with the robust mechanical properties of 3C-SiC. Using this approach we were able to fabricate SiC cantilevers for a new class of pressure sensor. In the present research, chemical vapour deposition (CVD) in the low pressure regime of 3C-SiC on silicon substrates was carried out using silane (SiH 4 ), propane (C 3 H 8 ) and hydrogen (H 2 ) as the silicon supply, carbon supply and gas carrier, respectively. The resulting bow in the MEMS structures was evaluated optically and the residual stress in the films calculated using the modified stoney equation and determined to be approximately 300 MPa.
Thickness dependence of the piezoresistive effect in p-type single crystalline 3C-SiC nanothin films
Journal of Materials Chemistry C, 2014
This paper reports, for the first time, the piezoresistive effect of p-type single crystalline 3C-SiC nanothin films grown by LPCVD at low temperature. Compared to thick SiC films, the gauge factors of the 80 nm and 130 nm films decreased remarkably. This result indicates that the crystal defect at the SiC/Si interface has a significant influence on the piezoresistive effect of ultra-thin film p-type 3C-SiC.
Electrical Properties of p-type 3C-SiC/Si Heterojunction Diode Under Mechanical Stress
IEEE Electron Device Letters, 2014
The current mechanism and effects of external transverse stress in the [110] orientation on the electrical properties of a single crystal (100) p-3C-SiC/p-Si heterojunction diode are reported for the first time. It has been observed that the current flow in the heterojunction is due to tunneling through the triangular potential barrier formed due to valence band offset between Si and SiC. The applied stress produces small changes in tunneling current when stress is increased from 0 to 308 MPa. The observed increase in current at 0.24 V is 10% at maximum stress of 308 MPa. The increase of tunneling current when applying stress is explained in terms of stress, which alters the out-of-plane effective mass, and the effective tunneling barrier height of holes in top subbands of p-type Si.