These results indicate that the microscopic mechanism of P diffusion in strained SiGe may have a small but non-negligible vacancy-mediated term. For each type of structure, several wafers were grown under identical growth conditions to be used as as-grown wafers and annealed wafers. The above experiments and analysis demonstrated a new approach in measuring segregation coefficients. However, there is no experimental study available on whether this method works for P in strained-SiGe systems and to what extent. To load this item in other compatible viewers, use this url: For example, for an n-type doped semiconductor, the diffusivity is expressed as:
Studies using RTP tools are in great need to be industry relevant. These adjustments do not affect the nitridation impact factor, as each set of samples for comparison 70 were annealed in the same run. To preserve the crystallinity, strained SiGe layers are grown on top of Si in such a way that the lateral in-plane lattice spacing is maintained while the vertical out-of-plane lattice spacing can expand or contract freely. As discussed in Ch. The results showed that the extent of B diffusion suppression in Si and Si0. Fundamentals, Practice and Modeling. There was an implicit assumption behind this equation that diffusivity is independent of concentration and of its gradient.
These results show that carbon can be used as a diffusion suppressing agent if the target dopant is an interstitial diffuser.
Base doping profile control for SiGe PNP HBTs – UBC Library Open Collections
For SiGe, the literature data for boron shows that the carbon impact factor RC is very close to that in Si, i. We can see that the segregation effect is more and more obvious as time increases, which is a dynamic process. As P prefers to stay in Si rather than in SiGe, this effect yhesis not desired for narrow P profiles, and needs to be taken into account in the mass transport modeling. Physically, tehsis base doping reduces electrical resistance, while narrower base doping profile Horizontal Vertical 4 reduces capacitance and carrier transit time in the base region.
For each type of structure, several wafers were grown ssige identical growth conditions to be used as as-grown wafers and annealed wafers. This means that these two layers are fully strained to the substrate during diffusion, and no strain relaxation was observed for the structures after diffusion.
In Chapter 6, we present the experiments and modeling of P segregation across graded SiGe layers. Show downloadable dissertations only. It is known that the equilibrium critical thickness reduces rapidly with increasing Ge fraction .
Is this difference important?
: SIGE HBT
Defect engineering methods such as carbon incorporation or thermal nitridation. The thin thickness of strained SiGe layer, tens of nanometers, poses a requirement for precise dopant profiling on the scale of angstroms. C and SIMS results to measure the carbon substitutionality, as discussed in 4. Their insightful questions and constructive advice helped me a thedis in improving my work.
C or the relaxed SiGe or the strained SiGe lattices, which were previously studied. C structures and annealed them in three different defect injection conditions, including the thermal nitridation vacancy injection condition. From the time evolution of P profiles as shown later in this articlewe can see that this ratio is not a constant.
Experimentally, the author designed all the sample structures and annealing conditions, prepared samples for secondary ion mass spectrometer SIMS.
Large-signal modeling and low-frequency noise characterization aspects University dissertation from Uppsala: One important feature about XRD measurement is that it only gives us information about the crystal structure, not the identity of atoms. The data points in diamonds are from Ref. For C molar fraction at 0.
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For the latter set of samples, the maximum Ge molar fraction is 0. From these references, one can see that a gap between experimental results and theoretical modeling still exists. The nitridation-induced suppression factor in the carbon-incorporated sample was weaker than in a carbon-free sample. Warren Poole for being the chairman of my oral examining committee.
These models are much easier to calibrate and implement than the dopant-defect reaction and transport equations. Models were established to calculate the effective P diffusivities as a function of carbon concentration. This topic will be discussed in Chapter 6. C diffusion tyesis seen to be much faster than P and Ge diffusion.
Interestingly, in Ge18C and Ge18C, the P profile under the nitridation condition is not showing any retardation, but rather a slight enhancement in P diffusion is seen.
Simple analytical solutions such as complementary-error function or Gaussian function do not apply to more complicated diffusion problems and many industry problems like the case of HBTs. This practical thickness limit depends on the epitaxial growth condition, the thickness of Si capping layer on top and the subsequent thermal budget .
The results indicate that a direct interchange is not favored in terms of energetic considerations. Bipolar transistors are so named because their operation involves both sieg and holes.