In-situ determination of the flat band carrier concentration and surface charge density of individual semiconductor nanowires by a combination of electrical and field emission measurements

摘要

The carrier concentration of semiconductor nanowires is one of the most important parameters for their nanoelectronic and optoelectronic applications. Because of their nanoscale geometry, the carrier concentration of nanowires is related to their flat band carrier concentration and surface charge density. Usually, these fundamental properties can be derived from the electrical transport and capacitance measurements of a nanowire field effect transistor (FET). Considering that the FET fabrication process can easily affect the nanowire surface, in-situ determination of these properties is of great interest. In this work, a method based on the chemical adsorption-induced surface band bending and field emission penetration effect was proposed to fulfill this task. Using this technique, the flat band earner concentration and the surface charge density of a free-standing ZnO nanowire were obtained to be 0.7-2 x 10~(18)cm~(-3) and 1.07-3.73 x 10~(12)e/cm~2, respectively. Compared with the conventional method based on a nanowire FET, this result provides a simple and nondestructive way to study these fundamental electrical properties of a nanowire.