On the Optimisation of SiGe-Base Bipolar Transistors

Extensive computer simulations of NPN SiGe-base bipolar transistors were performed to examine the effect of the Ge profile in the electrical characteristics. It is shown that extra charge storage in the emitter-base (E-B) junction, caused by the Ge profile, affects the device performance considerably. In addition, it is shown that an abrupt Ge profile in the middle of the base region is optimal for a given critical layer thickness of approximately 600A.

[1]  D. Harame,et al.  75-GHz f/sub T/ SiGe-base heterojunction bipolar transistors , 1990, IEEE Electron Device Letters.

[2]  J.W. Slotboom,et al.  Selective-epitaxial base technology with 14 ps ECL-gate delay, for low power wide-band communication systems , 1995, Proceedings of International Electron Devices Meeting.

[3]  M. H. Lyons,et al.  The structural stability of uncapped versus buried Si1−xGex strained layers through high temperature processing , 1989 .

[4]  J. Sturm,et al.  Base resistance and effective bandgap reduction in n-p-n Si/Si/sub 1-x/Ge/sub x//Si HBTs with heavy base doping , 1996 .

[5]  D.B.M. Klaassen,et al.  A unified mobility model for device simulation—I. Model equations and concentration dependence , 1992 .

[6]  R. People,et al.  Physics and applications of Ge x Si 1-x /Si strained-layer heterostructures , 1986 .

[7]  J. Slotboom,et al.  Unified apparent bandgap narrowing in n- and p-type silicon , 1992 .

[8]  F. M. Smits,et al.  Potential distribution and capacitance of a graded p-n junction , 1960 .

[9]  R.D. Gardner,et al.  A new approach to optimizing the base profile for high-speed bipolar transistors , 1990, IEEE Electron Device Letters.

[10]  J.W. Slotboom,et al.  Parasitic energy barriers in SiGe HBTs , 1991, IEEE Electron Device Letters.

[11]  J.M.C. Stork,et al.  High-low polysilicon-emitter SiGe-base bipolar transistors , 1993, IEEE Electron Device Letters.

[12]  J. Slotboom.  Analysis of bipolar transistors , 1977 .

[13]  Hu,et al.  Experimental study of diffusion and segregation in a Si-(GexSi1-x) heterostructure. , 1991, Physical review letters.

[14]  D.B.M. Klaassen,et al.  A unified mobility model for device simulation—II. Temperature dependence of carrier mobility and lifetime , 1992 .