Electrical characterization of locally charged oxidized nanocrystalline diamond films by Kelvin force microscopy

A nanocrystalline diamond (NCD) thin film is deposited on a gold electrode and oxygen terminated by r.f. oxygen plasma. An atomic force microscope (AFM) is used to induce electrostatically charged micrometer‐sized areas on the diamond film by applying bias voltages in the range between –30 V and +30 V on the AFM tip during scanning in contact mode. Trapped charge was detected by Kelvin force microscopy showing a contact potential difference of 150 mV for both polarities. Decrease of surface potential by 20 mV in the positively charged area and by 90 mV in the negatively charged area is observed after 15 h under ambient conditions. Possible charge trapping mechanisms are discussed in terms of electret‐like or semiconductor‐like behavior of NCD thin films. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)