Capture of carriers to screened charged centres and low temperature   shallow impurity electric field break down in semiconductors
  Free carrier capture by a screened Coulomb potential in semiconductors are considered. It is established that with decreasing screening radius the capture cross section decreases drastically, and it goes to zero when $% r_s=a_B^{*}$. On the basis of this result a new mechanism of shallow impurity electric field break down in semiconductors is suggested. 
O.Z.Alekperov