IMAGING AND MANIPULATION PROPERTIES OF NANOPARTICLES IN SCANNING-TUNNELING-MICROSCOPY

Nanometer-sized particles manufactured by two different techniques and deposited on wet chemically treated Si(111) substrates are explored a t room temperature with a scanning tunneling microscope (STM) in the l ight of their stability upon repeated imaging and the feasibility to m anipulate them with the probing tip. The two preparation techniques in clude field-induced transfer of Au from the STM tip stimulated by volt age pulsing and a wet chemical method. In the latter case, a colloidal solution of specified admixtures is prepared delivering CdS particles with a diameter of approximately 5 nm. In STM images, they protrude a s 50-nm-high isolated hillocks or as one particle-high islands contain ing a varying number of individual constituents. The STM imaging proce ss does not cause any changes in the structure of the islands or in th e position of single particles. Upon traversing the tip through partic le islands, several constituents can be removed. Depending on the depo sition conditions in the field-induced transfer mode, the created Au d eposits either adhere strongly to the substrate or they are displaced by the STM tip while imaging.