Characterization of 3C-silicon carbide for advance applications

Mohd Nasir, N 2012, Characterization of 3C-silicon carbide for advance applications, Doctor of Philosophy (PhD), Electical and Computer Engineering, RMIT University.


Document type: Thesis
Collection: Theses

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Title Characterization of 3C-silicon carbide for advance applications
Author(s) Mohd Nasir, N
Year 2012
Abstract 3C-Silicon Carbide (SiC) is a potential material for biomedical microdevices due to its excellent electrical, material and biocompatibility properties. Here, the fabrication processes for n-type 3C-SiC membranes using epitaxial 3C-SiC layers grown on Silicon (Si) substrate are presented and discussed in detail. Membranes of n-type 3C-SiC were fabricated using standard photolithography, reactive ion etching (RIE) and wet etching of Si substrates and could withstand small applied forces. Subsequently, the membranes were able to be patterned with patterns such as Circular Transmission Line Models (CTLM) patterns.

Scanning electron microscope (SEM) micrographs were used to observe the structure of the membranes. The quality of the 3C-SiC membranes were observed using Raman Spectroscopy and Visible Transmission Spectra. The remains of <111> Si substrate which was unetched during the Si wet etching were represented with the formation of microstructure defects which showed distinct peaks in comparison to the high quality 3C-SiC membranes at different position. X-Ray Photoelectron Spectroscopy (XPS) revealed the effect of RIE where fluorinated plasma had introduced fluorine elements into the membranes’ surface.

Surface modification due to reactive ion etching (RIE) process had significant impact on the electrical properties of the sample. The non linearity of current-voltage (I-V) characteristics for the samples treated with fluorinated plasma was observed which were absent for the control 3C-SiC samples. . Measurements of specific contact resistance, ρc for Al/3C-SiC and Pd/3C-SiC contacts with pre-treatment by reactive ion etching in CF4 plasma were 3 orders of magnitude higher (ρc = 2 x 10-1 Ωcm2) than for as-grown SiC or KOH treated surfaces (ρc = 4 x 10-5 - 8.9 x 10-4 Ωcm2). Annealing of Al/3C-SiC contacts resulted in a progressive increase in ρc with increase in temperature to 600 °C. In this program, it is found that the substrate effect on the electrical characteristic properties of 3C-SiC/Si can be neglected at room temperature. However, the application of 3C-SiC membrane to determine the electrical characteristics is the best way to eliminate any possibility of current leakage into the substrate for this type of system.

Cells grown on 3C-SiC were stellular and flattened showing good adhesion to the material as compared to cells on Si. The number of the cells grown on the 3C-SiC samples showed superior figure in comparison to Si which indicates higher biocompatibility. However, the number of cells was found to be less for the plasma treated samples, even compared with Si. This result was annulled after a series of experiments using typical assay used for cell viability detection such as MTT assay and PrestoBlueTM reagent where the plasma treated samples had the best cell viability percentage of all. By using hemolytic activity assessment, the plasma treated 3C-SiC was found to be decisively hemocompatible.
Degree Doctor of Philosophy (PhD)
Institution RMIT University
School, Department or Centre Electical and Computer Engineering
Keyword(s) Silicon carbide
ohmic contact
contact resistance
biocompatibility
hemocompatibility
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