Analysis of heavily doped semiconductors

Abstract

MSTRAm-An accurate determination of y(x)-integral appearing in Kane's expression for the density of states is presented. Expressions of this approach are compared with other existing approximations. Mock's model for total density of states is applied to illustrate possibilities of proposed derivations. An efficient algorithm for analyses of highly doped semiconductor material properties with Kane related models is introduced. Calculated dependence of pn product and screening length versus doping is given. The influence of different approaches met in the literature and in this work on calculated semiconductor parameters of importance such as minority carrier concentration and pn product is shown. INTRODUCTIOIIA variety of models for efficient highly doped semiconductor modeling can be found in the literature. This is a consequence of the tendency to describe heavily doped regions as accurate as possible yet to model mentioned areas sufficiently accurate, at acceptable complexity for device modeling. Band tail effect was among others described by Kane, who gave expressions for the density of states functions (1,Z). Evaluation of y(x)-integral (3) appearing in Kane's expressions is presented. Mock's model 161 for overall band description is applied to present the use of our derivations. Algorithm for pn product calculation is presented. A comparison of our derivations with approximate expressions given by Slotboom [SI is also reported.

Influence of Fermi-Dirac Statistics on Collector Current of npn SiGe HBT at Low Temperatures

“…As m,* is a function of temperature (T), doping concentration (N,? and Ge fraction (xGe) [6,7]], the magnitudes of Udeg and AEDOS,, depend on T, N i and xGe. eE,,, AED0,, and AEdeg+AEDos,, are presented on Fig.…”

“…1. The calculations are based on the model for m, " from [7]. As can be seen, AEdeg+AEDos,, is negative and its absolute magnitude increases rapidly with increasing doping concentration, increasing Ge fraction and decreasing temperature.…”