<p>This thesis deals with the development of high speed InPmesa HBTs with power gain cutoff frequencies up toand above 300 GHz, with high current density and low collectordischarging times.</p><p>Key developments are Pdbased base ohmics yielding basecontact resistances as low as 10 Ωµm<sup>2</sup>, basecollector grades to enable to use ofInP in the collector, and an increase in the maximum currentdensity through collector design and thermal optimization.HBTs with a linear doping gradient in the base are forthe first time reported and compared to HBTs with abandgap graded base. The effect of degenerate base doping issimulated, as well as the base transit time.</p><p>Key results include a DHBT with a 215 nm thick collector andan f<sub>τ</sub>= 280GHz, and f<sub>max</sub>=400 GHz. This represents the highest f<sub>max</sub>reported for a mesa HBT. Results also include aDHBT with a 150 nm thick collector and an f<sub>τ</sub>= 300 GHz, and f<sub>max</sub>=280 GHz. The maximum operating current densityhas been increased to above 10 mAµm while maintaining f<sub>τ</sub>and f<sub>max</sub>≥ 200 GHz.</p><p>A mesa DHBT process with and as much yield and simplicity aspossible has been developed, while maintaining or pushingworldclass performance.</p>
| Identifer | oai:union.ndltd.org:UPSALLA/oai:DiVA.org:kth-3527 |
| Date | January 2003 |
| Creators | Dahlström, Mattias |
| Publisher | KTH, Microelectronics and Information Technology, IMIT, Kista : Mikroelektronik och informationsteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, monograph, text |
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