Stabilized field emission behavior of diamond-like carbon-coated Si tips

Micromachined Si tips have been considered as a strong candidate for cold cathode materials. However, as-prepared Si tips showed unstable emission behavior, presumably due to native oxide, chemical reaction with residual gases or changes in tip geometry during operation. In order to stabilize the emission behavior, diamond-like carbon (DLC) films were deposited on the Si tips by DC magnetron sputtering of high purity graphite. We focused on the stability of the emission behavior by repeating the I-V measurement with anode voltages ranging from 100 to 2500 V. With increasing number of I-V measurements, the onset electric field decreased in both as-prepared and DLC-coated Si tips. However, the emission current of as-prepared Si tips decreased with increasing number of I-V measurements and eventually could not be observed after 10 measurements. On the other hand, DLC-coated tips exhibited improved emission behavior by repeating the I-V measurement. These results showed that the DLC coating can prevent the Si tips from oxidation or from being contaminated, which stabilized the field emission behavior. Furthermore, the DLC coating seems to reduce the effect of the changes in tip apex morphology by reducing the sharpness of the tip apex. (C) 1999 Elsevier Science S.A. All rights reserved.