SSL/NUSNNI Seminar Series 2004 No.2

Combined talks (two speakers)

Date: April 26 (Monday), 2004
Time: 4:00-5:00pm
Venue: Physics Resource Room (Blk S13 # 02-16)

Speaker I: Mr. Chung Hong Jing
Title: Nanoscale fabrication using atomic force microscopy probe induced oxidation

Abstract:
Atomic force microscope (AFM) probe induced oxidation process is based on negatively biasing the tip with respect to the conductive substrate. The possibility of such local oxidation is a promising method for the nanolithography and nanofabrication of devices for various applications. In this talk, we demonstrate that different types of oxide feature can be fabricated including lines, complicated polygon shapes, plain platforms, and also dots. The influence of experiments parameters, such as tip bias voltage and tip scanning velocity on the lateral and vertical growth of oxides are analyzed throughout a series of experiments on n-type silicon (100). The possible mechanism involved in the AFM probe induced localized anodic oxidation are discussed.

Speaker II: Mr.Yong Kian Soon
Title: Nanopatterning of Silicon Surfaces

Abstract:
Scanning tunneling microscope (STM) was used to investigate the formation of Cu nanostructures on the Si(111)-7?7 surface. Cu forms clusters preferentially on the faulted halves of the 7?7 unit cells and the modified surface was intended to be used as a template to organize the growth of thiophene and phthalocyanine. It was shown that thiophene adsorbs on the Cu clusters while leaving the Cu-uncovered halves intact. Phthalocyanine, however, interacts with the Si dangling bonds on the unfaulted halves and does not pattern according to the ordered Cu clusters. Besides, the (2?n) surface structure formed upon deposition of Ge on Si(100)-2?1 was also used as a template to organize the positions of subsequently deposited molecule. The adsorption of styrene on this (2?n) surface was investigated using STM and it was found that a 1-D molecular nanostructure was formed through the selective binding of styrene to the Ge=Ge dimer.