Analysis Of Heterojunction Bipolar Transistors Research Articles

Low frequency conductance voltage analysis of Si/Ge/sub x/Si/sub 1-x//Si heterojunction bipolar transistors

Low-frequency-conductance-voltage (LFGV) method for analysis of heterojunction bipolar transistors (HBTs) is presented. The method gives accurate quantitative values for the important minority-carrier transport parameters that underlie the transistor performance, such as the base diffusion length, lifetime, diffusion coefficient and transit time. The method also allows a detailed analysis of the current gain and emitter injection efficiency. The analytical model and experimental methodology are demonstrated for a Si/Ge/sub x/Si/sub 1-x//Si HBT with a trapeziodal and linearly graded Ge profiles in the base. The LFGV method is general and can be applied to other bipolar transistors, including those based on III-V materials.

Bipolar transistor vertical scaling framework

Scaling factors for current and transit time are derived for polysilicon emitter, silicon based heterojunction bipolar transistors. It is shown that a simple set of analytical equations in integral form can be used to analyse the above scaling properties and by introducing two “heterojunction factors” can be extended to the scaling analysis of heterojunction bipolar transistors.

A three dimensional semiconductor device simulator for GaAs/AlGaAs heterojunction bipolar transistor analysis

A three-dimensional semiconductor device simulator was developed to study the steady-state characteristics of heterostructure compound semiconductor devices. The semiconductor partial differential equations-Poisson's equation and the two carrier transport equations-are solved using finite-difference discretization. The Gummel iteration method and indirect space matrix solution techniques are utilized for minimizing computation time and memory requirements. This simulator was applied to the analysis of heterojunction bipolar transistors. The effect of emitter grading on the current-voltage characteristic is demonstrated. A comparison between two- and three-dimensional simulations is also presented. The results show that three-dimensional analysis is indispensable, in particular for devices of small geometry. >

Monte Carlo approach to transient analysis of HBTs with different collector designs

The transient analysis of heterojunction bipolar transistors (HBTs) using the Monte Carlo technique is presented. Three HBT structures with conventional (A), inverted field (B), and undoped (C) collectors were simulated. The transient behavior of the collector currents show that the time constants are 1.466, 0.722, and 0.863 ps at a collector current of 3.5*10/sup 4/ A/cm/sup 2/ for devices A, B and C, respectively. This suggests that the inverted field structure may be the best choice for high-speed applications. >