Free carriers silicon

Fig. 28. Representation of a hydrogenated field effect transistor. The carrier concentration in the active layer is controlled, before the gate deposition, by the hydrogen neutralization of the donors present in the highly silicon doped layer. The insert shows the free carrier concentration gradient from the gate, which results from the hydrogen diffusion. J. Chevallier and M. Aucouturier, Ann. Rev. Mater. Sci. 18, 219 (1988). Annual Reviews Inc.

Figure 9. Calculated absorption due to free-carriers in 500-pm thick n-type silicon containing 5 x 10 to 1 x 10 donors/cm (Reproduced with permission from Ref. Copyright...

Correlations between the free-carrier concentration and the RT resistivity have been made for n- and p-type silicon by Irvin [22] as a function of the dopant concentration (cm-3) assuming no compensation. From these measurements, in n-type silicon with p > 1.4 flcm, Np or n is about 5.0 x 1015 p 1 and in p-type silicon with p > 0.9 il cm, Np or p is about 1.3 x 1016 p 1. For a more extended range in P-doped silicon, see [52]. 

Dean et al [7] measured the Zeeman splitting of a luminescence line involving the 2p donor state, obtaining the electron effective mass m t=(0.24 0.01)mo and m /m, =0.36 0.01 for n-type cubic crystals. Measurements of infrared Faraday rotation due to free carriers were made by Ellis and Moss [8] at room temperature in a number of n-type hexagonal specimens belonging to the 6H and 15R polytypes of silicon carbide. One component of the total density-of-states effective mass was explicitly determined by this method. A value for the... 

Porous silicon (por-Si) formed by electrochemical etching of (llO)-oriented p-type Si wafers is an example of novel nanostructured medium with controllable optical properties. It was found to exhibit the strong in-plane birefringence (up to 18 %) and free-carrier dichroism [1-5]. Both phenomena originate from the form anisotropy of Si nanocrystals and voids assembling the material [3-5]. Below, we report the analysis of the dichroism in por-Si on the basis of the generalized effective-medium approximation (EMA) [7] as well as prominent anisotropy of absorption by silicon-hydrogen surface bonds. 

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