Mg-Doping of GaAs (111)B Thin Films Grown by Molecular Beam Epitaxy

In this work, the influence of the growth conditions in the incorporation of Mg p-type dopant atoms in epitaxial GaAs(100) and (111)B thin films was investigated. Hall effect measurements and photoluminescence spectroscopy were used to investigate the electrical and optical properties of the films, respectively. The doping level varied between 1016 and 1019 cm–3 and increased with the inverse of the growth temperature and with the temperature of the Mg evaporation cell, with similar behavior in both crystal orientations. The analysis of the Mg incorporation at several growth temperatures and Mg arrival rates established a value of Ed(111)B = 1.6 ± 0.1 eV for the thermal desorption activation energy of Mg in the GaAs(111)B, a value 33% higher than for the (100) case. However, when a more realistic incomplete ionization model for the acceptors is considered, the value of the thermal activation energy for desorption of Mg adatoms increases to 2.7 ± 0.8 eV and equals the value for the (100) surface. Two very ...