LOW-FREQUENCY NOISE IN UHV CVD EPITAXIAL SI AND SIGE BIPOLAR-TRANSISTORS/

In this work a comprehensive investigation of low-frequency noise in u ltrahigh vacuum/chemical vapor deposition (UHV/CVD) Si and SiCe bipola r transistors is presented, The magnitude of the noise of SiGe transis tors is found to be comparable to the Si devices for the identical pro file, geometry, and bias. A comparison with different technologies dem onstrates that the SiGe devices have excellent noise properties compar ed to AlGaAs/GaAs heterojunction bipolar transistors (HBT's) and conve ntional Si bipolar junction transistors (BJT's), Results from differen t bias configurations show that the 1/f base noise source is dominant in these devices. The combination of a 1/Area dependence on geometry a nd near quadratic dependence on base current indicates that the 1/f no ise sources are homogeneously distributed over the entire emitter area and are probably located at the polysilicon Si interface, Generation/ recombination (G/R) noise and random telegraph signal (RTS) noise was observed in selected Si and SiGe devices. The bias dependence and temp erature measurements suggest that these G/R centers are located in the base-emitter space charge region, The activation energies of the G/R traps participating in these noise processes were found to be within 2 50 meV of the conduction and valence band edges.