Dislocation effects on carrier concentration for molecular-beam-epitaxially grown GaAs

Dislocation effects on carrier concentration for Si-doped and Si-implanted molecular-beam-epitaxially (MBE) grown GaAs layers are investigated by small area (40×40 μm2) Hall measurements. It is found that there is no correlation of carrier concentration with dislocation density and distance from a dislocation to a Hall device. The photoluminescence 1.51-eV bound exiton peak and the 1.49-eV carbon acceptor peak intensity variations are small across a wafer. Moreover, there are no variations in high-resolution photoluminescence intensity and in electron-beam-induced current image between positions close to and far from a dislocation. These results indicate that carrier concentration is not affected by dislocations in MBE-grown epilayers because of the absence of a denuded zone around the dislocation. Acceptors and/or point defects are depleted in liquid-encapsulated Czochralski-grown GaAs, whereas this does not take place during the MBE growth processes.