Changes in Conductivity of Germanium Induced by Alpha-Particle Bombardment

Abstract

The bombardment of $n$-type germanium by alpha-particles from polonium first removes the conducting electrons at the rate of 78 per alpha-particle. After the electrons are gone conducting holes are introduced at the initial rate of 8.6 per alpha-particle. Some of these holes disappear with time at room temperature after bombardment is stopped, leaving only two conducting holes per alpha-particle. This change takes place only to the depth of penetration of the particles, namely 1.9\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ cm. The distribution of holes with depth is not uniform. The concentration rises from an initial value to a maximum at 1.4\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ cm depth and then falls to zero. The maximum is about 2.5 times the initial value and the integral under the curve is, of course, two holes per alpha-particle.