Graphene computer components holds the possibility of increasing computer speeds into the 1-100 terahertz range. This is a significant advance towards making that and other graphene electronic and computer applications possible.
Room temperature on/off current ratio of 100 is by no means the upper limit of the graphene FET.
In summary, we demonstrated a bi-layer graphene transistor with an on/off current ratio of around 100 at room temperature. The transport measurement indicates a Schottky barrier height >65 meV at Dave of 2.2 Vnm-1, corresponding to an electrical (transport) bandgap of >130 meV. At 20 K, a device on/off current ratio of about 2000 is demonstrated at Dave of 1.3 Vnm-1. Revealing of the large electrical bandgap in bi-layer graphene may enable a number of novel nanoelectronic and nanophotonic applications.
The fabrication steps of the dual-gate bi-layer graphene field effect transistor (FET) are described as follows:
1. Identification of bi-layer graphene flakes using optical approach and Raman spectroscopy. The bi-layer graphene flakes in this experiment were purchased from Graphene Industries, Inc.
2. First e-beam lithography and source/drain metallization (Ti/Pd/Au/Ti: 0.5/20/20/5 nm).
3. Second e-beam lithography and patterning of the bi-layer graphene channel.
4. Spin coating of the organic seed layer made from a derivative of polyhydroxystyrene (the polymer NFC 1400-3CP manufactured by JSR Micro, Inc.) for atomic layer deposition (ALD). The layer thickness can be adjusted by spin speed. The dielectric constant of this material is about 2.524.
5. Atomic layer deposition of top gate oxide (HfO2) at T < 2000C. 6. Third e-beam lithography and top gate metallization (Ti/Au: 5/25 nm). Poly methyl methacrylate (PMMA) was used as the e-beam resist in all the processing steps mentioned above. Removal of PMMA was realized using acetone and usually was followed by isopropanol rinse. No specific surface cleaning steps were involved in the processing.
A list of recent Mesoscale and Nanoscale Physics papers in arxiv