Measurements of the temperature dependence of electron-hole pair creation in silicon nuclear radiation detectors
Key, James Roy
Rabson, Thomas A.
Master of Science
The semiconductor radiation detector may be looked upon as a solid-state ionization chamber in which the energy of incident radiation is dissipated, resulting in the creation of electron-hole pairs in the detector medium. The purpose of this thesis was to measure e as a function of temperature, where e is the average energy required to create an electron-hole pair in a silicon detector. If these devices are to be used to make absolute measurements of particle energy, it is imperative to know the value of e. Experimentally, the response of a detector to radiation was observed as a voltage pulse height. The pulse height displayed a repeatable dependence on detector temperature. The pulse rise time was examined for possible effects of dielectric relaxation. Various corrections were applied to the pulse height to arrive at an absolute value of e. The response of a lithium-drift silicon detector to radiation from ThC' a's and Bi207 conversion electrons was noted over a temperature range of 20-300°K. It was inferred from experimental data that from 25°K to 20°K, s experienced a rapid 33% increase from 3.95 + or - 0.035 e.v. to 5.28 + or - 0.035 e.v. It was concluded that dielectric relaxation effects were not significant, since the pulse rise time was not temperature dependent.