Electrical determination of bandgap narrowing and parasitic energy barriers in SiGe and SiGeC heterojunction bipolar transistors

Abstract

In this paper a novel electrical method is described which allows the extraction of bandgap narrowing within the base of SiGe heterojunction bipolar transistors due to heavy doping effects and the presence of germanium. In addition it is shown that the methods sensitivity to doping tails makes it ideal for determining the presence of parasitic energy barriers due to B outdiffusion from the base, a cause of major concern for HBT technology. The analysis is applied to SiGe and SiGeC HBTs showing that background carbon incorporation (R 1020m2-3) completely suppresses TED.

Empirical Process Model for Arsenic Diffusion in Si_1-x-yGe_xC_y Alloys

“…Earlier work by Anteney et al [8] suggests the dependence of intrinsic carrier concentration on temperature and band-gap energy:…”

SiGe HBTs for application in BiCMOS technology: I. Stability, reliability and material parameters

“…Considerable work on these topics has been done at Princeton University [19], at IMEC [20][21][22][23][24] and by other groups [25][26][27][28]. Recently several papers have appeared on the mobility [29][30][31][32][33] and on BGN [34][35][36][37]. Simulations and material parameters are discussed in section 4.…”

“…Anteney et al [35] 0.20 7 -Matutinovic-Krstelj et al [34] a 1-7 -Matutinovic-Krstelj et al [34] Apparent BGN E diff g,t,app versus Ge mole fraction for several doping and Ge concentrations given in table 2. The data points of Matutinovic-Krstelj et al [34] and Anteney et al [35] are for E SiGe g,t,app (see text).…”

“…Anteney et al [35] 0.20 7 -Matutinovic-Krstelj et al [34] a 1-7 -Matutinovic-Krstelj et al [34] Apparent BGN E diff g,t,app versus Ge mole fraction for several doping and Ge concentrations given in table 2. The data points of Matutinovic-Krstelj et al [34] and Anteney et al [35] are for E SiGe g,t,app (see text). Straight line 1, strain-induced BGN E g,x in the undoped SiGe layers; 2-4, calculated values of E diff g,t,app for N A = 7 × 10 18 , 5 × 10 19 and 1 × 10 20 cm −3 respectively.…”

“…The scatter in the experimental data is very large and they agree with the theoretical values only approximately. The data points of Matutinovic-Krstelj et al [34] and Anteney et al [35] are the values of E g,t,app for SiGe layers and not E diff g,t,app because these authors did not fabricate the Si control transistors. They plotted ln J C (HBT) versus 1/T .…”