Bipolar transistor with large band-gap emitter material - uses single crystalline silicon as emitter and collector and forms base-region from silicon-germanium cpd.

摘要

The bipolar transistor uses as base-region (2) a Si-Ge cpd., with the compsn. Si(X)Ge(1-X) and a value of X from 0.05-0.2 (0.1), which has been deposited by low pressure vapour phase epitaxy (LPVPE). The emitter (3) material is single crystalline Si, pref. deposited after the base-material by LPVPE. The selective depsn. of base and emitter regions is achieved by using a masking layer (4,5) of thermal or pyrolytically deposited SiO2 or of Si-nitride. USE/ADVANTAGE - The construction combines the advantages of an emitter material with a larger bandgap than the base-material with that of good lattice-fit allowing single crystalline material, to be used. This results in low leakage currents and lower resistivity. The emitter, doped e.g. to a level of 10 power 17 cm (-3), has a gap of 1.1 Ev, the base material has a gap of 1.0 Ev. The devices are used for HF operation or as fast switching transistors.