A lattice model of nearest-neighbor hopping conduction and its application to neutron-doped Ge: Ga

A model of hopping conduction between nearest neighbors is developed in which the majority and compensating dopant atoms are assumed to form a unified simple cubic lattice in a crystalline matrix. The hopping of carriers occurs when thermally activated “equalization” of majority impurity levels takes place, while the compensating impurities block the corresponding sites. The range of relatively high temperatures is considered in which the interactions giving rise to a Coulomb gap can be neglected and the density of states of the majority impurity band is Gaussian. The concentration dependences of the activation energy for hopping conductivity ? ₃ (nonmonotonic and having a maximum) and the preexponential factor σ₃ are found. The results are compared with experimental data obtained by different authors for neutron-doped Ge: Ga.