Graphene base transistors (GBTs) are known to be novel devices mingling outstanding properties of graphene, with the concept of hot electron transistors (HETs). According to theoretical calculations, GBTs were predicted to have over 5 orders of magnitude ON/OFF current ratios and THz frequency range operations. This would in fact lead to potential applications in high speed radio frequency (RF) analog devices. Recently, GBTs’ high gain and more than 4 orders of magnitude ON/OFF current ratios have been experimentally proven. However, GBTs still need further improvements before they can be applied in real electronics devices; and that can be done through thickness and barrier height optimization of the tunneling barrier. In this thesis project, we have studied various gate dielectrics for potential applications as tunneling barriers in GBTs. To accomplish this study, we have gone through two rounds of successful cleanroom fabrication processes, where we fabricated fully functional devices. During the first round, we have developed seven different capacitor structures on 4 inch Si wafers with ALD deposited: Al2O3, TiO2, HfO2, “Al2O3+TiO2 mix”, SiO2/HfO2 stack, SiO2/Al2O3 stack and thermally grown SiO2 dielectrics. Whereas in the second batch, BG-GFET structures were fabricated on chip level, with: 2nm SiO2, 5nm SiO2, 10nm SiO2, (2nm/4.2nm) SiO2/HfO2, (2nm/4.5nm) SiO2/”Al2O3+TiO2 mix”, 6nm “Al2O3+TiO2 mix” and 6.6nm TiO2 bottom gates, onto which a single layer graphene was transferred. We have also carried out electrical characterizations of these successfully fabricated devices and making use the encouraging results obtained, we have investigated the associated current injection mechanisms across each barrier / <p>QC 20150115</p>
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-143206 |
| Date | January 2013 |
| Creators | Belete, Melkamu |
| Publisher | KTH, Mikroelektronik och tillämpad fysik, MAP |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | TRITA-ICT-EX ; 238 |
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