Nano-scale process and device simulation
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The Ohio State University / OhioLINK
2005
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu11253402882021-08-03T05:50:17Z Nano-scale process and device simulation Ravichandran, Karthik CNT Si/SiO2 Nanotube dopant electron <p>With the tremendous increase in computational power over the last two decades, computer simulation has become an indispensable tool in device engineering. In this work, atomistic simulation based on ab-initio density functional theory (DFT) was used in modeling Si-based Metal Oxide Semiconductor Field Effect Transistors (MOSFET) and Carbon Nanotube Field Effect Transistors (CNTFET).</p> <p>In the case of MOSFETs, the dopant dose loss due to segregation and pileup at the Si/SiO2 interface have a strong influence in device performance, especially in the deep submicron regime. The previously suggested segregation model for arsenic at Si/SiO2 interfaces based on a combined trapping/pairing model [J. Dabrowski, H.-J. Mussig, V. Zavodinsky, R. Baierle, and M. J. Caldas, Phys. Rev. B 65, 245305 (2002)] requires high binding energies for the interface vacancies, which our results of ~0.2 eV cannot confirm. As an alternative explanation, we present ab initio results that show that As and hydrogen bond with an energy gain of 1.5-3 eV with their minimum-energy position at the interface, which creates additional trapping sites for As segregation. The inclusion of hydrogen into the modeling might thus be able to explain the perceived differences between the previous model and experiments.</p> <p>With the continuous downscaling of MOSFETs, the physical limits for the current Si based CMOS technology will be reached, in terms of device dimensions and materials properties, within the next few years. The future transistors will be based on molecular electronics, like carbon nanotubes, utilizing their ballistic electron transport property. In CNTFETs, the nanotube/metal contact forms a crucial region which exerts considerable influence on the device characteristics, similar to the role of pn-junctions in traditional MOSFETs. Whereas in MOSFETs the junction formation is reasonably well understood and can be virtually engineered by process simulation within technology computer aided design (TCAD), such a capability does not really exist to date for molecular devices. Here, we suggest such molecular process modeling and study the evolution of the atomic structure of the contact between Ti-metal and a CNT by ab-initio temperature-accelerated dynamics and the respective change in the electron transport properties. Our results indicate that the CNT disintegrates on top of Ti to form a flat graphene-like structure causing a decrease in the current through the device by one order of magnitude in comparison to the optimum structure, in agreement with experiments. Thus, we show that the use of “molecular process simulation” to follow the evolution of the appropriate contact structure for the interface is a key factor in modeling electron transport through molecular devices.</p> 2005-08-29 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1125340288 http://rave.ohiolink.edu/etdc/view?acc_num=osu1125340288 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
CNT Si/SiO2 Nanotube dopant electron |
| spellingShingle |
CNT Si/SiO2 Nanotube dopant electron Ravichandran, Karthik Nano-scale process and device simulation |
| author |
Ravichandran, Karthik |
| author_facet |
Ravichandran, Karthik |
| author_sort |
Ravichandran, Karthik |
| title |
Nano-scale process and device simulation |
| title_short |
Nano-scale process and device simulation |
| title_full |
Nano-scale process and device simulation |
| title_fullStr |
Nano-scale process and device simulation |
| title_full_unstemmed |
Nano-scale process and device simulation |
| title_sort |
nano-scale process and device simulation |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
2005 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1125340288 |
| work_keys_str_mv |
AT ravichandrankarthik nanoscaleprocessanddevicesimulation |
| _version_ |
1719426342438567936 |