A PIN dosimeter is modern dosimeter, which can give a continuous readout of cumulative dose and current dose rate, and can warn the person wearing it when a specified dose rate or a cumulative dose is exceeded. PIN dosimeters are based on semiconductor chip. Semiconductor detectors are based on ionization in a solid (e.g. silicon) and include different types of solid-state devices with two terminals called diodes. For example a silicon diode, which has a p-i-n structure in which the intrinsic (i) region is sensitive to ionizing radiation, particularly X rays and gamma rays. Under reverse bias, an electric field extends across the intrinsic or depleted region. In this case, negative voltage is applied to the p-side and positive to the second one. Holes in the p-region are attracted from the junction towards the p contact and similarly for electrons and the n contact.