Models and method of calculation of doping and injection-dependent impurity density of states in GaAS

Abstract

Using the solution to the problem of screened Coulomb potential for the low-doping regime, the theories of Morgan and of Halperin and Lax, respectively, for the medium- and high-doping regimes, the conduction-and valence-band impurity density of states of GaAs are expressed in explicit analytic forms and calculated self-consistently. The effects of injection and doping on the density of states are studied. To avoid the self-consistent iterative process but still take into account the effects of screening, a method of calculation for the density of states is obtained. It is shown that in many cases, the screening length can be determined using the Boltzmann approximation or the parabolic-band approximation. The region of validity for each approximation in the injection-doping space is found. Density of states calculated using these approximations are compared with density of states calculated self-consistently.