Nanostructure formation via electrochemical reaction

• Main Author: Wang, Joyce Xiangyi.
• Other Authors: Pey Kin Leong
• Format: Final Year Project
• Language: English
• Published: 2009
• Subjects: DRNTU::Engineering::Electrical and electronic engineering::Microelectronics
• Online Access: http://hdl.handle.net/10356/18001
• Institution: Nanyang Technological University

Nanostructure has been very popular with researchers as it an object of intermediate size between molecular and microscopic, which is very small in size (in the order of 10-9 m), which poses as a great potential for future applications. There are many types of Si wafers with crystalline orientations sold in the market. The two main Si wafers that were used in this project would be Si(100) and Si(111). Various methods using different parameters such as types of etching solution, durations for etching, concentration of nanosphere colloidal solutions etc. were used to form nanowires/nanostructures. In addition, the overall fabrication processes on how the nanowires were formed were also discussed. The wet bench is a place where most of the experiments such as etching, mixing of solutions were held. After all the processes have been done, the samples were sent for viewing using the scanning electron microscopy. It has the ability to view the nanowires/nanostructures in nanometer range. Another equipment used for this project is the reactive ion etching machine. It is used to shrink the diameters of the nanospheres to aid the etching of the samples to form nanowires. There are 4 main experiments discussed in chapter 4 of this report. Experiment 1 consists of etching Si, SiGe (9% Ge), SiGe (20% buffer on Si) and Ge samples with different etching times. It is found out that that longer the etching time, the longer the length of the nanowires would be, except for the case of Si substrate. Experiment 2 talks about the formation of nanowires using unconventional method of etching mono and multi layer nanospheres on silicon substrate without going through the RIE process. It results in creating holes at the small gaps in between the nanospheres for the mono layer case and irregular surface roughness for multi layer case. Experiment 3 mentioned about etching 5 samples of 1.5 nm, 3 nm, 5 nm, 10 nm, 20 nm gold and 20 nm nickel n-type Si(100) samples together with annealing and etching. Using the SEM, nanowire/ nanostructure formation can only be seen on 10nm and 20nm gold samples. The last experiment is regarding the etching of amorphous-silicon samples. After etching for a short duration, it is realized that the layer of amorphous was etched away.