| AVS 54th International Symposium | |
| Thin Film | Tuesday Sessions |
| Session TF-TuM |
| Session: | Two-Dimensional Carbon Nanostructures |
| Presenter: | M.Y. Zhu, College of William and Mary |
| Authors: | M.Y. Zhu, College of William and Mary R.A. Outlaw, College of William and Mary K. Hou, College of William and Mary P. Miraldo, College of William and Mary D. Manos, College of William and Mary |
| Correspondent: | Click to Email |
Two-dimensional carbon nanosheets were previously deposited by radio frequency plasma enhanced chemical vapor deposition (PECVD) using CH4/H2 plasma on a variety of substrates. In this work, we report the deposition of the same nanostructure using C2H2/H2 plasma at a substrate temperature more than 100 ºC lower than that for typical depositions using CH4/H2 plasma. The decrease of required substrate temperature is a great benefit to device fabrications. Carbon nanosheets were deposited on silicon substrates at temperatures ranging from 500 ºC to 600 ºC while other parameters were 100% C2H2 gas (5 sccm total gas flow rate), 35 mTorr gas pressure, 1000 W input RF power, and 10 minutes deposition duration. For substrate temperature from 550 ºC to 600 ºC, the carbon nanosheets deposited have sheet-like structures and flat surface morphologies, and are free-standing on substrate surfaces, as characterized by scanning electron microscope (SEM). High-resolution transmission electron microscopic (HR-TEM) results revealed that the edges of the nanosheets consist of about 3-8 atomic layers. Selected area electron diffraction pattern of carbon nanosheet samples matches that for polycrystalline graphitic structures. Raman spectra of carbon nanosheets have the characteristic D and G peaks for defective sp2 graphitic structures. Detailed results showed faster growth rates and high Raman D/G peak ratios for samples deposited at higher substrate temperatures. Carbon nanosheets were also deposited using various (60-100%) C2H2 in H2 concentrations while other parameters were fixed at 600 ºC substrate temperature, 5 sccm total gas flow rate, 1000 W input RF power, and 10 min deposition duration. With a decreasing C2H2 in H2 concentration, both the nanosheet growth rate and the Raman D/G ratio were decreased, however, the basic nanosheet structures were maintained. Cross-sectional SEM images showed that carbon nanosheets deposited using C2H2/H2 gas mixture have a straighter vertical orientation and a more uniform sheet height distribution than those deposited using CH4/H2 mixture, therefore are expected to have improved field emission properties. Field emission from C2H2/H2 carbon nanosheets are measured under diode configuration and the results will also be presented.