| AVS 54th International Symposium | |
| Thin Film | Tuesday Sessions |
| Session TF-TuM |
| Session: | Two-Dimensional Carbon Nanostructures |
| Presenter: | K. Hou, College of William and Mary |
| Authors: | K. Hou, College of William and Mary R.A. Outlaw, College of William and Mary M.E. Kordesch, Ohio University M.Y. Zhu, College of William and Mary P. Miraldo, College of William and Mary B.C. Holloway, Luna Innovations Incorporated D. Manos, The College of William and Mary |
| Correspondent: | Click to Email |
Carbon nanosheet, a novel two-dimensional carbon nanostructure consisting of vertically oriented ultra-thin graphitic sheets terminating with 1-3 graphene layers, are fabricated by inductively coupled radio frequency plasma enhanced chemical vapor deposition. Carbon nanosheet, with its atomic-scale edge structure, high purity, and uniform height distribution have been confirmed to be a promising candidate for the application as the cold cathode material in vacuum electronic devices. In this study, we present the latest field emission test results of carbon nanosheet thin film including total current, lifetime in a slow pulse mode, and lifetime in a dc mode. These tests were conducted using a diode configuration having an anode-cathode distance of 254 µm. Further, the emission uniformity of carbon nanosheet thin films was primarily studied by photoelectron emission microscopy. To date, we have routinely achieved total currents of more than 20 mA from ~30 mm2 while maintaining a useful current density of ~0.1 A/cm2. Among them, a maximum total current of 26 mA has been measured from a 32 mm2 testing area at an applied electric field of 25.5 V/µm. The test result suggests that the field emission of nanosheet film is not saturated at this field level but is limited by the test apparatus. The lifetime in a slow pulse mode was conducted by applying a series of identical voltage ramps over a long time period with a duty factor of 21%. The maximum current on the order of 13 mA in each voltage ramp was recorded for 96 hours. The test result reveals that the standard deviation of the maximum is less than 2.1%. The lifetime in a dc mode was conducted by applying a constant negative bias to the sample. A stable ~1.5 mA emission current was obtained from the carbon nanosheet thin film for 200 hours. The standard deviation of the emission current is less than 3.6% during the test period. Photoelectron emission microscopy was used to investigate the field emission uniformity over the surface of carbon nanosheet thin films. In addition, field emission electron microscopy images, formed without photon illumination, were also captured. The analysis of these images show that a small number of nanosheet emission sites dominate the emission current.