Silicon p-n Junction Radiation Detectors

Silicon p-n junction particle detectors have been fabricated by diffusing phosphorus to various depths between 0.1 and 2.0 μ into high resistivity p-type silicon. Various base material resistivities have been employed, ranging from 100 Ω cms to 13,000 Ω cms. Diffusions have been carried out both by the "gaseous" and the "paint-on" process. The devices produced have ranged in area from 1 mm
²
to 1 cm
²
, with the majority of detectors having an area of ~.2 cm
²
. Using 5.5 mev α particles and a 5 × 5 mm device, the best line width that has been obtained Is 20 kev. It has been found that the 1 cm
²
devices give line widths of ~ 50 kev. The effect of the thickness of the n layer forming the front surface of the junction has been investigated, and it has been shown that 0.1-μ diffusions give essentially "windowless" detectors. Other properties that have been examined are space charge generation of leakage current, charge collection efficiency as a function of bias and incident particle direction, and signal rise time.