Diodes As Ionizing Radiation Detectors and Temperature Measurements |

ABSTRACT:

Fromthe Shockley ideal diode equation it might appear that the voltage has a positive temperature coefficient (at a constant current),but usually the variation of thereverse saturation current term is moresignificant than the variation in the thermal voltage term. Most diodestherefore have a negative temperaturecoefficient, typically −2 mV/˚C for silicon diodes at room temperature. This isapproximately linear for temperatures above about 20 kelvins. Some graphsare given for: 1N400x series, and CY7 cryogenic temperaturesensor. In electronics, cosmic rays and other sources ofionizing radiation cause noise pulses and single and multiple biterrors. This effect is sometimes exploited by particle detectors todetect radiation. A single particle of radiation, with thousands or millions ofelectron volts of energy, generates many charge carrier pairs, as itsenergy is deposited in the semiconductor material. If the depletion layer islarge enough to catch the whole shower or to stop a heavy particle, a fairlyaccurate measurement of the particle's energy can be made, simply by measuringthe charge conducted and without the complexity of a magnetic spectrometer,etc. These semiconductor radiation detectors need efficient and uniform chargecollection and low leakage current