15 GHz f/sub max/ microwave silicon p-n- rho transistors with single-crystal emitters fabricated with simple four mask process

Vertical pnp transistors have been fabricated using a four mask, low cost quasi-selfaligned process with submicrometre feature sizes. The resulting monocrystalline emitter devices achieve ft greater than 9 GHz and fmax greater than 15 GHz with BVceo greater than 13 V. These discrete pnps were used successfully as active loads for a monolithic npn opamp to achieve a gain-bandwidth product of 4.4 GHz.