Shallow Impurity Cluster States in n-Type Semiconductors

摘要

Shallow impurity states are discussed for n-type semiconductors with emphasis on influence of the cluster states, type of disorder and many valley character of the indirect gap semiconductors. The random nature of the system is taken into account by analytical and simulation formalisms for the noninteracting one-band model and Hubbard and unrestricted Hartree-Fock-Roothaan models for correlated electrons. It is shown that in a wide range of impurity concentrations, such formalisms explain many of the electronic properties of doped semiconductors. The impurity states for a two-dimensional system are also discussed.