Analytical modelling of Early voltage and Current Gain of Si1−yGey Heterojunction Bipolar Transistor

Analytical modelling of Early Voltage (VA) and Common Emitter Current Gain (β) of Heterojunction Bipolar Transistor (HBT) are derived considering field dependent mobility, doping dependent mobility, Band Gap Narrowing (BGN), changes in density of state (DOS) and velocity saturation effect. BGN was considered due to heavy doping and presence of Germanium. The effect of various base doping profiles (Gaussian, exponential and uniform) and germanium profile (trapezoidal/triangular/box) on VA and β are addressed. The results of the analysis are compared with the data available in the previous research work.

[1]  Herbert Kroemer,et al.  Two integral relations pertaining to the electron transport through a bipolar transistor with a nonuniform energy gap in the base region , 1985 .

[2]  C. R. Selvakumar,et al.  Profile design considerations for minimizing base transit time in SiGe HBTs for all levels of injection before onset of Kirk effect , 2001 .

[3]  A. Jakubowski,et al.  The Influence of Selected Material and Transport Parameters on the Accuracy of Modeling Early Voltage in SiGe-Base HBT , 2006, IEEE Transactions on Electron Devices.

[4]  Jin-Hau Kuo,et al.  An accurate knee current model considering quasi-saturation for BJTs operating at high current density , 1995 .

[5]  S. Jain.  Germanium-silicon strained layers and heterostructures , 1994 .

[6]  A. Jakubowski,et al.  Modeling of SiGe-base heterojunction bipolar transistor with gaussian doping distribution , 2001 .

[7]  Kunihiro Suzuki,et al.  Base transit time of shallow-base bipolar transistors considering velocity saturation at base-collector junction , 1992 .

[8]  J. Sturm,et al.  Current gain-Early voltage products in heterojunction bipolar transistors with nonuniform base bandgaps , 1991, IEEE Electron Device Letters.

[9]  R. M. Swanson,et al.  Simultaneous measurement of hole lifetime, hole mobility and bandgap narrowing in heavily doped n-type silicon , 1985, 1985 International Electron Devices Meeting.

[10]  K. Suzuki,et al.  Optimum base-doping profile for minimum base transit time considering velocity saturation at base-collector junction and dependence of mobility and bandgap narrowing on doping concentration , 2001 .

[11]  S. Basu.  Analytical modelling of base transit time of SiGe HBTS including effect of temperature , 2008, 2008 International Semiconductor Conference.

[12]  Chih-Wen Liu,et al.  Base transit time of graded-base Si/SiGe HBTs considering recombination lifetime and velocity saturation , 2004 .

[13]  Alain Chantre,et al.  500 GHz cutoff frequency SiGe HBTs , 2007 .

[14]  H. C. de Graaff,et al.  Measurements of bandgap narrowing in Si bipolar transistors , 1976 .

[15]  P. K. Basu,et al.  Effect of Ge content and profile in the SiGe base on the performance of a SiGe/Si heterojunction bipolar transistor , 2005 .