the impact of temperature or doping or alloy composition. A single value may not take into account the required dependencies, e.g. However, in some analyses, this assumption is not sufficient. The simplest assumption is that the material parameters are constant for a given temperature or set of device parameters.
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In calculating semiconductor devices, both material parameters and devices parameters need to be specified as a function of each other and on the device operating conditions. Interdependencies among material, device and operating parameters While these approaches can calculate some material parameters accurately, it can be difficult to find theoretical material parameters for some cases. Since the Schrodinger Equation cannot be exactly solved in most cases relevant to semiconductor, there are multiple approaches to numerically performing such calculations, such as density functional theory (DFT) or ab initio. To find these, we need to solve the Schrodinger Equation. In new materials or for which there is not an extensive experimental base, the empirical approaches may not be available, and a theoretical calculation of the extended band diagram and phonon dispersion curve may be needed. Recombination parameters including the minority carrier lifetime (or the diffusion length), the surface recombination, the defect level and the defect energy the absorption coefficient The mobility (or diffusivity), which are related by the Einstein relationship The intrinsic carrier concentration and N C and N V The goal of these notes is to give these equations and the values used in the equations. If we know the extended energy band and the phonon dispersion curve, we can calculate the parameters, but more often it is more accurate and simpler to have semi-empirical or empirical equations for the material parameters. k diagram or dispersion curve) and by the phonon dispersion curves for phonons.Ī key simplification for semi-classical analysis in semiconductors is that the complexities of the extended band diagram can be incorporated into semiconductor device equations via material parameter models. For electrons, the band structure is represented by the extended energy band diagram (also called E vs. Theoretically, from the periodic arrangement of the constituent atoms, we can calculate the band structure for electrons and phonons. The properties of a material are most fundamentally determined by its crystal structure. Why do we need empirical material parameter models? In this set of notes, we focus on such dependencies for the material parameters. In other cases, we need to take into account the dependence of the material parameter on factors such as material composition, doping, temperature or injection level.
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Please see the site for data and other sources of data on the material parameters. For some applications, the material parameters can be considered a constant for a certain set of conditions. A semiconductor device consists of a combination of material parameters, which are a property of the material (e.g., mobility, band gap, effective mass, etc) and device-dependent parameters, which are specified by the device structure and fabrication sequence (e.g.