4.1
4
Electrodynamic basics
In this chapter we introduce the basics of electrodynamics that are required for solar cell
physics. First, we introduce the electromagnetic wave equations. The existence of these
equations explains the existence of electromagnetic waves, such as light. From there we
develop the equations describing the interaction of an electromagnetic wave with
interfaces between two materials; in this way we naturally derive the basics of optics.
Later in the chapter we introduce the Poisson equation and the continuity equations
that are very important for semiconductor physics, which we discuss in Chapter 6.
The electromagnetic theory
While electricity and magnetism have been known since ancient times, it took until the
nineteenth century to realize that these two phenomena are two sides of the same coin,
namely electromagnetism. We can easily see this by recalling that electric fields are
generated by charges while magnetic fields are generated by currents, i.e. . moving
charges. Let us now assume that we are within an array of charges. Since charges create an
electric field, we will experience such a field. Now we start moving with a constant
velocity. This is equivalent to saying that the array of charges moves with respect to us.
Since moving charges are a current, we now experience a magnetic field. Thus, when
changing from one frame of reference into another that moves with respect to the first one
with a constant velocity, electric fields are transformed into magnetic fields and vice versa.
Between 1861 and 1862, the Scottish physicist James Clerk Maxwell published
works in which he managed to formulate the complete electromagnetic theory by a set of
equations, the Maxwell equations. A modern formulation of these equations is given in
Appendix A.1. The transformation of the electric and magnetic fields between different
frames of reference is correctly described by Albert Einstein’s theory of special relativity,
published in 1905.
One of the most important predictions of the Maxwell equations is the presence of
electromagnetic waves. A derivation is given in Appendix A.2. Maxwell soon realized that
the speed of these waves is (within experimental accuracy) the same as the speed of light,
4
Electrodynamic basics
In this chapter we introduce the basics of electrodynamics that are required for solar cell
physics. First, we introduce the electromagnetic wave equations. The existence of these
equations explains the existence of electromagnetic waves, such as light. From there we
develop the equations describing the interaction of an electromagnetic wave with
interfaces between two materials; in this way we naturally derive the basics of optics.
Later in the chapter we introduce the Poisson equation and the continuity equations
that are very important for semiconductor physics, which we discuss in Chapter 6.
The electromagnetic theory
While electricity and magnetism have been known since ancient times, it took until the
nineteenth century to realize that these two phenomena are two sides of the same coin,
namely electromagnetism. We can easily see this by recalling that electric fields are
generated by charges while magnetic fields are generated by currents, i.e. . moving
charges. Let us now assume that we are within an array of charges. Since charges create an
electric field, we will experience such a field. Now we start moving with a constant
velocity. This is equivalent to saying that the array of charges moves with respect to us.
Since moving charges are a current, we now experience a magnetic field. Thus, when
changing from one frame of reference into another that moves with respect to the first one
with a constant velocity, electric fields are transformed into magnetic fields and vice versa.
Between 1861 and 1862, the Scottish physicist James Clerk Maxwell published
works in which he managed to formulate the complete electromagnetic theory by a set of
equations, the Maxwell equations. A modern formulation of these equations is given in
Appendix A.1. The transformation of the electric and magnetic fields between different
frames of reference is correctly described by Albert Einstein’s theory of special relativity,
published in 1905.
One of the most important predictions of the Maxwell equations is the presence of
electromagnetic waves. A derivation is given in Appendix A.2. Maxwell soon realized that
the speed of these waves is (within experimental accuracy) the same as the speed of light,