Physical Review B vol:45 issue:20 pages:11863-11875
The Ohmic-contact formation mechanism in furnace alloyed Au/Te/Au/(n -type GaAs) structures is investigated by the combined application of Mossbauer spectroscopy, x-ray diffraction, Raman scattering, and Auger-electron-spectroscopy depth profiling. A dominant shallow-donor-dopant behavior of the Te atoms (substitutional on As sites) can be questioned. The observed low-resistance conductivity is related to the presence of a (n+-type Ga2Te3)/(n -type GaAs) heterojunction. Although the possibility of some residual n-type doping of the GaAs substrate remains, evidence is adduced that, in the Ohmic-contact formation mechanism, at least an equally important role is played by a degenerate As n-type doping of the Ga2Te3. Similar arguments are developed for the (Au-Ge)/(n-type GaAs) and Ge/Pd/(n-type GaAs) Ohmic-contact systems.