Semiconductor junction detectors have many advantages for applications in low-energy nuclear physics, and no experiment with charged particles should in future be designed without full consideration of the possibilities of the new detectors. The design of amplifiers has already been influenced by the requirements of semiconductor counters, but there are still many problems in handling and storing the wealth of data that can be obtained with a number of detectors operated simultaneously. Conduction counters are at present at an earlier stage of development, but in many ways are simpler to understand than junction counters. This chapter discusses the applications of semiconductor counters in nuclear physics. The study of semiconductor detectors and their response to nuclear radiation provides a valuable new method of investigating the solid-state physics of semiconductors. There are many possible experiments in this field if only those who practise these two branches of physics can be brought together. Advances in the physics of semiconductors and in the technology of their preparation will make new developments in radiation detectors possible.