If different materials are used for emitter and base regions, a heterojunction is created at the emitter-base junction and this BJT becomes an HBT. The Ge dependence can be explained by the increasing contribution from the vacancy-assisted mechanism for P diffusion in strained SiGe with the increasing Ge content. Parameters such as chemical reaction rates, equilibrium concentrations and diffusivities of all mobile species are required to solve these equations. In particular, we discuss the relationship between macroscopic impurity diffusion and the underlying microscopic diffusion mechanisms in elemental semiconductors like silicon. If it is the case, it is a relatively low cost and simple approach to be adopted by industry, as the only change is in the annealing ambient. These results indicate that the microscopic mechanism of P diffusion in strained SiGe may have a small but non-negligible vacancy-mediated term. In contrast, for oxynitridation, phosphorus and boron diffusion was enhanced while antimony diffusion was retarded.
In the following discussions, we refer to native point defects simply as point defects unless otherwise noted. Defect engineering methods such as carbon incorporation or thermal nitridation. Yuanwei Dong, my former lab mate, for many brain-storming discussions and for proofreading my first paper. Therefore, we approximated the P diffusivity in SiGe with a simple linear function of Ge molar fraction. SIMS is based on the fact that charged atomic and molecular species are ejected from the surface of a sample under heavy particle bombardment.
As Si-Ge interdiffusion is much slower than P diffusion, annealed Ge profiles are very close to the as-grown Ge profiles; 67 therefore, only Ge as-grown profiles are shown for clarity. Cy lattice spacing under different strain status: Newman and Wakefield concluded that, in bulk monocrystalline silicon, carbon resides predominantly on substitutional sites based on the observations that the diffusion coefficient and the activation energy of carbon are similar to those of the dopants .
They showed that the Sb diffusion enhancement factor was smaller in Si0. This uncertainty was taken into account in our simulations. These questions will be address as Topic 2 in Chapter 5.
It simulates the incorporation and redistribution of impurities in a 2-D cross-section theeis a silicon wafer. Empirical models were established to calculate the carbon impact on the time-averaged point defect concentrations and effective diffusivities as a function of carbon content. C structures and annealed them in three different defect injection conditions, including the thermal nitridation vacancy injection condition. Proceedings of the Meeting,pp.
For each type of structure, several wafers were grown under identical growth conditions to be used as as-grown wafers and annealed wafers. From these references, one can see that a gap between experimental results and theoretical modeling still exists. However, there is no study available on whether this method also works in strained-SiGe system and if any to what extent. It has hbh unique advantages including its non-destructive nature, a good match of X-ray wavelength to the atomic scale of crystal structure and the rapid collection of statistically significant data .
Therefore, we had to find another method to simulate the coupled diffusion-segregation 28 phenomenon. Ghesis dashed parts are extrapolation using the Eseg values. Popular searches water supply activities distributed optimization engineering thesis e eye locus of control class group Chalmers University Of Technology work ability Chemical technology and engineering water resources traffic information.
The impact of carbon and Ge on P diffusion in strained SiGe: It should be noted that carbon concentrations measured from SIMS are total carbon concentrations regardless of the carbon positions in the lattice. As a comparison, relevant literature data are also plotted in this Figure Ref. This task requires the understanding of diffusion and the use of various phenomenological and atomistic theories.
Base doping profile control for SiGe PNP HBTs – UBC Library Open Collections
From the time evolution of Tbesis profiles as shown later in this articlewe can see that this ratio is not a constant. Perhaps it should be attributed to heat, or thermal processing, which prevailed in the Bronze and the Iron Age. For high-speed and high-frequency applications, there are two important figures-of-merit: Mary Jansepar, and Ms.
However, it was not able to take the Ge concentration gradient introduced segregation flux into account.
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Large-signal modeling and low-frequency noise characterization aspects University dissertation from Uppsala: In contrast, for oxynitridation, phosphorus and boron diffusion was enhanced while antimony diffusion was retarded.
The theoretical derivations of coupled diffusion and segregation model of this work is generic to all inhomogenous solid solutions, and the experiments and model calibration are specifically relevant to PNP SiGe HBTs.
Point defect concentrations can be disturbed by using either external sources such as ion implantation, oxidation, nitridation and proton irradiation or internal sources such as the incorporation of another species.
Thus, thesid are always probabilities for the atoms with higher energy to be too active to stay in their original positions. If this method is effective, it is a relatively low cost and simple approach that can be tgesis by industry, as the only change is in the annealing ambient.
C under rapid thermal anneal conditions siige studied quantitatively. In Chapter 4, we present a systematic and quantitative study of carbon impact on P diffusion in strained SiGe through experiments and modeling.
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