A semiconductor particle detector is a device that uses a semiconductor (usually silicon) to detect the passage of charged particles or photons. In the field of particle physics, these detectors are usually known as silicon detectors.
Most silicon detectors work, in principle, by doping narrow (usually around 100 micrometres wide) strips of silicon to make them into diodes. As charged particles pass through these strips, they cause small leakage currents which can be detected and measured. Arranging thousands of these detectors around a collision point in a particle accelerator can give an accurate picture of what paths particles take. Silicon detectors have a much higher resolution in tracking charged particles than older technologies such as cloud chambers or wire chambers. The drawback is that silicon detectors are much more expensive than these older technologies and require sophisticated cooling for their electronics as well as suffer degradation over time from radiation.