Oxidation-enhanced diffusion contributions

Equation 36 is divided into the contributions to the diffusion of substitutional impurity under nonoxidizing conditions, DSI, and the enhanced contribution due to oxidation, AD0. Figure 16 shows the data of Taniguchi et al. (44) for oxidation-enhanced diffusion of P and B versus the total number of dopant impurities per square centimeter, QT. The calculated values of DSI and AD0 are shown in comparison with the experimental data. Reasonable agreement is obtained. Thus, Taniguchi s model of self-interstitial recombination with vacancies is consistent with the models of high-concentration diffusion of B and P used by Fair in his calculations. 

Figure 16. Measured and calculated values of boron and phosphorus diffusiv-ities as a function of total impurity doping. Data are divided into contributions to substitutional impurity diffusion under nonoxidizing conditions, DSj, and the enhanced contribution due to oxidation, AD0. Data are from Taniguchi et al. (44). (Reproduced with permission from reference 45. Copyright 1981 The Electrochemical Society, Inc.)...

The oxidation rate of the micro- and nanopowders was found to be faster than that of bulk single-crystal silicon, hich can be rationalized as follows. At the initial stages of the oxide growth oxygen adsorption on micro- and nanoparticles leads to SiO formation. The oxidation is then due to an enhanced oxidant diffusion over the particle surface. During the oxidation of the powders, the amount of the oxidant penetrating into the bulk of a particle is so small that its contribution to the oxidation process in the bulk of the particle is insignificant. In this case, the oxidation of the micro- and nanopowders is... 

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