الفهرس 
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Abstract
Semiconductor device simulation had seen considerable progress in the past 50 years. It has evolved from initial theoretical formulation into sophisticated tools that can simulate the properties of a wide variety of semiconductor devices. There is no doubt that such device simulation has aided growing of semiconductor industry by predictive analysis and even trouble-shooting of device design. At present, as the semiconductor integrated circuits continue to increase in complexity and density, the underlying devices continue to get smaller, faster and more complex in their behavior. Therefore, it is expected that device sinlUlation will continue to be the most effective way to design devices with desirable properties. The models used to sinlUlate these propeliies are basically a set of partial differential equations (PDEs) that describe the device behavior. The solution of this set of equations depends on the specific structure and geometry of device and applied field [I].
In this thesis, the analysis of the second harmonic component of optical wave generated• in semiconductor media is our issue. Semiconductors are widely used as nonlinear optical (NLO) materials. Second harmonic generation (SHG) is one of the most famous NLO processes. The SHG in semiconductors has wide applications such as: frequency conversion [2], disease diagnosis [3], surface analysis studies [4], retardation measurements [5], etc.
In this thesis, device level sinlUlation of the optical SHG inside an I1-type 6mm noncentrosymmetric semiconductor, when a highly intense optical wave propagates inside it, is presented. This model allows simulating nonlinearity of semiconductor media that comes due to the contribution of second order nonlinear susceptibility or field-carrier interaction.
Many efforts were done before in the field-carrier interaction of an electromagnetic (EM) wave propagating inside semiconductor [6-14]. They combined Maxwell’s equations with the carrier-transport model. But, all these models aren’t applied to the highly intense laser Also SHG of the intense laser have gained an interest since 1962 when 1. A. Armstrong, N. Bloembergen et aI. issued a pioneer paper [15] in such field and presented the method of solving the coupled system in terms of Jacobean elliptic function. The SHG of optical wave propagation is a field of interest till now [16-17]. But, they considered only the second order NLO polarization as a source term in the Maxwell’s equations. All the macroscopic models presented for the SHG problem haven’t taken the effect of the charge carriers in semiconductor device in consideration.
In this thesis, a new model is presented simulating the SHG problem inside an n-type 6mm noncentrosymmetric semiconductor considering drift and diffusion of charge carriers. Inside the noncentrosymmetric semiconductor, the nonlinear second order susceptibility is nonvanishing. The model is mainly based on four set of equations:
Maxwell’s equations, carrier transport model of semiconductor, continuity equation, and NLO polarization equation. Then, these set of equations were solved by the finite element method (FEM) using the COMSOL commercial simulator. The simulation showed that the charge carriers accumulated at the boundaries. This thesis opened many nlture points of research which will be discussed later.