Charge carrier statistics of semiconductors containing defects with negative electronic correlation energy

The free charge carrier concentration as a function of the reciprocal temperature and the doping level [p(1/T)- andp(C)-characteristics] is calculated from the neutrality equation of a semiconductor containing positive or negativeU centers. The typical exponential laws and power laws of thep(1/T)- andp(C)-characteristics are given both for positive and negative correlation energy of the bound charge carrier pairs. Furthermore, the characteristics are evaluated differentially, in order to obtain criteria for the presence of negativeU centers in semiconductors.Work partly performed while on leave at the IBM Thomas J. Watson Research Center, Yorktown Heights, NY 10598, USA