You are invited to attend a lecture
By
Eliezer Halpern
(Ph.D. student under the supervision of Prof. Yossi Rosenwaks)
School of Electrical Engineering, Tel-Aviv University, Tel-Aviv 69978, Israel
Nanoscale-Electronic Characterization of InAs
Semiconductor nanowires (NWs) are one of the most promising building blocks for miniaturization, as well as a wealth of opportunities for pursuing nanoscale science, in particular mesoscopic physics, as well as a vast number of technological applications. Understanding their surface properties is crucial in developing both new electronic devices, as well as providing insight for future fundamental research. In this work we have studied InAs NWs, and investigated two main phenomena - surface states and quantum confinement. The former has a large effect on the performance of both electronic and optoelectronic devices. At present, determination of the surface state density is achieved via measurements of the capacitance and/or drain current, in a nanowire field-effect transistor, and fitting it to simulation. These methods rely on certain assumptions, which strongly affect the extracted density of states. In this work, we demonstrate direct measurement of the surface state density and energy distribution in individual nanowires, in the range of 1012-1013 cm-2eV-1. The measurement was done using Kelvin Probe Force Microscopy (KPFM), which is a highly sensitive method for detecting nm-scale work function variations. In the second part of the work, we have shown energy sub-bands formed due to quantum confinement; this observation was carried at room temperature, again using the KPFM. The extracted density of states and quantum confinement in nanowires is of importance in understanding the electronic overall performance of InAs nanowires in part, and of all semiconducting nanowires as a whole.
Monday, May 25, 2015, at 15:00
Room 146, Electronic Labs building