The first edition of Semiconductor Physics was published in spring 2018, in time for Karl W. Böer’s 92nd birthday and only a month before he died. The book has been well received by the scientific community. Semiconductor devices are ubiquitous in our daily life, and today the global semiconductor industry is a key driver for economic growth. Recent discoveries in semiconductor physics established new and intriguing fields, which will open new scopes for applications in the future. One such field refers to the electronic states in a topological insulator, which recently led to a new classification scheme for electronic phases in condensed matter and in principle enables dissipationless surface conductance. Another field is quantum optics with the realization of photonic qubits based on excitonic states; rapid progress presently opens prospects for realizing quantum communication and quantum computing. Much of these developments are intimately related to the basic principles of semiconductors physics; some of the new topics are addressed in the second edition, keeping the style and the conciseness of the presentation. In addition, the initial text is thoroughly amended and updated.