Gate assisted Kelvin test structure to measure the electron and hole flows at the same nanowire contacts
A gate assisted Kelvin test structure based on Si nanowire field effect transistors has been designed and fabricated for the characterization of the transistor source/drain contacts. Because the Si nanowire field effect transistors exhibit ambipolar characteristics with electron current slightly lower than the hole current, we can select the type of carriers (electrons or holes) flowing through the same contacts and adjust the current by the applied gate voltage. In this way, we are able to measure the characteristics of the same contact with either pure electron or hole flow. In addition, we found that the nanowire contacts behave very differently depending on the current flow directions. This indicates that the source and drain contact resistance can be dramatically different. Such a gate assisted Kelvin Test structure will lead to future metrology and applications in nanoelectronics.