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In the previous post we discussed silicon, which is the most used material in photovoltaics. In this post, we introduce the band diagram, for which we will use silicon as an example. We will start our discussion of the band diagram with the Bohr model of the silicon atom. In semiconductor materials the outer shell of the atom, which is called the valence shell, is not completely filled. The outer shell of silicon contains 4 out of the possible 8 electrons, which we call valence electrons. As we discussed in the previous post, each silicon atom in a crystalline structure is bonded to four other silicon atoms. The bonds between the silicon atoms are called covalent bonds. These bonds actually consist of two valence electrons that are shared by two silicon atoms. All valence electrons are fixed in the lattice, forming covalent bonds, and are therefore immobile. However, at a temperature above absolute zero, thermal energy is supplied to these miconductor and some of the vale

Welcome to this new post about semiconductor physics. Before we delve into all the important topics of semiconductor physics that are relevant to solar cells, we need to talk about silicon. Silicon is one of the most important materials when it comes to solar cells and we will be using it throughout this post series as an example for all the semiconductor concepts we will be going into. This will only be a short introduction to silicon, and there will be an extensive post series on silicon-based solar cells in the following course, Photovoltaic Technologies. Let’s start our discussion by looking at the reasons why silicon is the most used material for fabricating solar cells. The first successful silicon solar cell was fabricated in the Bell Laboratories in US in 1954. At present, the photovoltaic industry is dominated by silicon-based solar cells with 90%share of the market. Silicon is the most widespread material used for solar cells. But why is it that silicon is used so much?

Welcome to this first post about semiconductor physics. During this course you will learn about the properties of a semiconductor as a photo-active material for solar cells. I will introduce you to the topics that we will cover during the coming weeks. Semiconductors are materials that are widely used for several applications. We can find them in electronic devices such as diodes, transistors or integrated circuits. But for us, they play a crucial role as active materials in solar cells. But, what is a semiconductor? Let’s define this term. We will do this by looking at important material properties that define a semiconductor. When we look at material’s ability to conduct electricity they are generally divided into three classes: conductors, semiconductors, and insulators. A semiconductor is a material whose electrical conductivity is lower than the one of a conductor, but higher than that of an insulator. One example of a semiconductor material is Silicon. Solar cells made of