| About this Abstract |
| Meeting |
2011 Electronic Materials Conference
|
| Symposium
|
2011 Electronic Materials Conference
|
| Presentation Title |
L6, Deposition and Characterization of AlN Dielectric Films on Graphene |
| Author(s) |
Mark Fanton, Joshua Robinson, David Rearick, Michael LaBella, Kathleen Trumbull, Randal Cavalero, Matthew Hollander, Zachery Hughes, David Snyder |
| On-Site Speaker (Planned) |
Mark Fanton |
| Abstract Scope |
Traditional semiconductor field effect structures rely on the use of thin oxide films to isolate the gate electrode from the channel. The use of oxides on carbon-based structures presents some unique challenges considering the high thermodynamic driving force for reaction between carbon and oxygen. In this work AlN was successfully used as a dielectric for fabricating field effect structures on epitaxial graphene on semi-insulating SiC. A process was developed for deposition of 5-10nm thick AlN films on graphene by molecular beam epitaxy (MBE). Films were grown by RF-plasma-assisted MBE at deposition temperatures between 50°C and 350°C. Careful initiation of growth was critical for avoiding damage to the graphene film. Damage due to exposure to the N-plasma as well as metal rich growth initiation was studied via Raman spectroscopy. Al-rich growth conditions resulted in significant increases in the Raman D/G peak ratio. X-ray photoelectron spectroscopy (XPS) indicated that this was due to Al-C chemical bonding, which is thermodynamically favorable in the absence of N. Similarly, the N-plasma power and gas flow rate were found to significantly impact defect generation in the graphene film. The optimum plasma conditions are discussed in terms of the flux of molecular N and charged species. Near simultaneous introduction of the N-plasma and the Al source resulted in little or no damage to the graphene films as characterized by Raman spectroscopy. Prior to deposition of AlN the graphene films exhibited a mobility of 800cm2/V-s, and a sheet carrier density of 8x1012cm-2, as measured by Hall effect. In the worst cases, after deposition of the dielectric the mobility decreased to as low as 350cm2/V-s and the carrier concentration increased to as much as 1.5x1013cm-2. Changes in mobility and carrier concentration will be discussed in terms of structural changes observed by Raman spectroscopy and transmission electron microscopy and changes in chemistry as monitored by x-ray photoelectron spectroscopy. The dielectric properties of the AlN films will be discussed in terms of relative dielectric constant and dielectric loss as a function of frequency up to 1GHz. |
| Proceedings Inclusion? |
Undecided |