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. Key developments are Pdbased base ohmics yielding basecontact resistances as low as 10 Ωµm2, 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. Key results include a DHBT with a 215 nm thick collector andan fτ= 280GHz, and fmax=400 GHz. This represents the highest fmaxreported for a mesa HBT. Results also include aDHBT with a 150 nm thick collector and an fτ= 300 GHz, and fmax=280 GHz. The maximum operating current densityhas been increased to above 10 mAµm while maintaining fτand fmax≥ 200 GHz. A mesa DHBT process with and as much yield and simplicity aspossible has been developed, while maintaining or pushingworldclass performance.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-3527 |
| Date | January 2003 |
| Creators | Dahlström, Mattias |
| Publisher | KTH, Mikroelektronik och informationsteknik, IMIT, Kista : Mikroelektronik och informationsteknik |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Doctoral thesis, monograph, info:eu-repo/semantics/doctoralThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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