Selfaligned AlGaAs/GaAs HBT grown by MOMBE
- 6 June 1991
- journal article
- Published by Institution of Engineering and Technology (IET) in Electronics Letters
- Vol. 27 (12) , 1054-1056
- https://doi.org/10.1049/el:19910655
Abstract
The very low parasitic resistance npn GaAs/AlGaAs heterojunction bipolar transistors (HBT) grown by metal organic molecular beam epitaxy (MOMBE) using all gaseous source dopants are reported. The carbon and tin dopants were introduced through the uses of trimethygallium (TMGa) and tetraethyltin (TESn). To achieve the low parasitics, the graded InGaAs emitter cap layer was doped with tin to 5 × 1019cm−3 and the doping level in the subcollector was 3 × 1018cm−3. The emitter and collector sheet resistances were 25Ω/□ and 10Ω/□, respectively. The 800 Å thick base layer was carbon doped to a level of 7 × 1019cm−3. The base contact resistance and sheet resistance were 0.1 Ωmm and 180Ω/□, respectively. With a thin AlGaAs surface passivation layer for the emitter–base junction, the common emitter DC current gain was maintained up to 25, even for 2 × 5 μm2 emitter size devices. The unity short circuit current gain cutoff frequency fT and maximum oscillation frequency fmax, were 48 and 63 GHz, respectively.This publication has 0 references indexed in Scilit: