Modulation And Applications Of 4H-SiC Nanostructures Realized By Electrochemical Etching

Silicon carbide,as the third generation of semiconductor, has a number of unique properties, such as wide band-gap, high thermal conductivity, high breakdown electric field. These advantages make it to replace silicon and applied in the special fields of high temperature, high frequency and high power. In the background of increasing requirements of chip integration, the modulation process of silicon-based nanostructure becomes mature.Although the Si C-based nanostructures were fabricated by various methods, 3C-Si C nanostructures were the focus of the investigation. Following that, modulation of 4H-Si C based nanostructures has attracted much more attention in recent years. Nowadays, 4H-Si C can be produced commercially in wafer scale, which ensures that the relevant devices, based on the wafer, process the feasibility of mass production. In order to combine 4H-Si C nanostructures with 4H-Si C based system on chip(SOC), electrochemical etching process will be applied in 4H-Si C nanostructure modulation in the thesis. The work can be concluded as following:At the beginning of the study, we set up relevant mechanism model to explain the phenomenon of side-well etching during electrochemical etching n-Si, which plays a role in guiding the electrochemical etching n- type 4H-Si C in the following investigation. In study of electrochemical etching of n type 4H-Si C, the mesopores array, with same diameter along etching direction, was fabricated by introducing pulsed current source. The problem “the diameter being widened as the etching time going” was therefore completely solved.In study of 4H-Si C nanowires array fabrication, 4H crystalline, oriented nanowires array was obtained by electrochemical etching. The length andmorphology of nanowires could be modulated by changing current mode. The diameter of each nanowire is in nanoscale and the length could be modulated between nanoscale and microscale. To our knowledge, the nanowires array is first realized.In term of the application, silicon carbide possesses the potential value in high temperature application, under the current research interests on flexible field emission and supercapacitor, we focus on the realization of high temperature flexible/ high temperature field emission cathode and supercapacitor as final goal.The work mainly proceeded on the relevant characterization of 4H-Si C nano-structures. In characterization of field emission behavior of 4H-Si C nanowires array, the maximum value of field enhanced factor reached 7901 when the distance between anode and cathode was set at 700?m while the turn on field reached 0.86V?μm-1.In characterization of capacitor of 4H-Si C mesopores array, the specific capacitor reached 450 ?F?cm-2.