In-situ phosphorus-doped polysilicon emitters deposited on monocrystalline silicon substrates at a temperature of 627°C and subjected to no additional high-temperature annealing are shown to be capable of giving Gummel numbers GEin excess of 1015scm-4. Polysilicon emitters formed in this way have been used to produce superbeta transistors with performance comparable to the record levels recently reported for MIS emitter devices. In particular, common-emitter current gains β in excess of 30000 have been obtained at low VCBvalues.