Semiconductor device physics and modelling. 1. Overview of fundamental theories and equations

The mathematical physics related to semiconductor materials and devices is reviewed, and its relevance and application to the commonly used semiconductor device equations and models is discussed. An overview is given to provide a methodical link between the fundamental theories and equations. The fundamental theories start from the wave and particle properties of electrons and the statistics of free carriers in semiconductors. This, together with the effective mass concept, leads to the energy band structure of semiconductors. Based on the principle of momentum conservation and the free-carrier statistics, the author also derives the Boltzmann transport equation, which is considered the most fundamental equation for semiconductor device physics. The widely used drift-diffusion equations are then obtained from the Boltzmann transport equation by using several assumptions such as the relaxation-time approximation and that the semiconductor is isothermal. A summary of the basic equations used in classic device physics is also included