CALCULATION OF CARRIER CONCENTRATIONS AND FERMI ENERGIES IN INTRINSIC AND DONOR-DOPED IN 1-XGAXAS

The carrier concentrations and Fermi energies are calculated for intrinsic and donor-doped In1-xGaxAs alloys over the entire composition range and temperatures between 77 and 300 K. The calculation of the electron density in the conduction band as a function of the Fermi energy is carried out using an established k.p method to take into account of the nonparabolicity of the bands. A fourth-order polynomial is fitted to the composition dependence of the bandgap at 0 K, and temperature dependence of both bandgap and effective mass are also taken into account. The donor density at which InAs, In0.53Ga0.47As and GaAs become degenerate at 300 K are about 1 x 10(17), 2 x 10(17) and 4 x 10(17) cm-3, respectively.