A number of δ-doping parameters have been changed to study their effects on the hole concentration of Zn δ-doped GaAs grown by metalorganic vapour phase epitaxy using dimethylzinc (DMZn) as a doping precursor. We observed that the hole concentration is dependent on the DMZn partial pressure but independent of the gas flow velocity in the reactor. A weak effect of the δ-doping time on the hole concentration infers that the near-equilibrium between the Zn adsorption and desorption can be reached very rapidly. In the regime of the δ-doping temperatures from 600 to 700°C, the Zn desorption predominantly determines the hole concentration, and the Zn desorption activation energy obtained from the Arrhenius-type plot is 2.04 eV. Below 600°C, however, the hole concentration departures from the Arrhenius-type relationship with the reciprocal δ-doping temperature, indicating that some other factors start to influence the Zn δ-doping concentration.