Growth of Si δ-doped GaAs by low pressure metal organic vapour phase epitaxy

The influence of various growth parameters on the carrier concentration of Si δ-doped GaAs by low-pressure metal-organic vapour phase epitaxy has been investigated. The Si δ-doping activation energy obtained from the Arrhenius plot of the carrier concentration versus the reciprocal temperature is 0.85 eV and its dependence on the growth conditions is discussed. The carrier concentration decreases with increasing the pre-δ-doping purge time under a constant arsine partial pressure. A high V/III ratio for growth of the undoped GaAs buffer and cap layers cladding the d -doped layer leads to a low carrier concentration. The desorption of the Si doping species from the non-growing GaAs surface is proportional to the post-δ-doping purge time and is promoted by the arsine partial pressure. We also found that the residence time of the Si dopants in the reactor is the dominant factor that determines the carrier concentration; in contrast, the silane partial pressure only plays a minor role.