Photocurrent study of molecular beam epitaxy GaAs grown at low temperature

Photocurrent spectroscopy measurement has been utilized to study low temperature behavior of molecular beam epitaxy GaAs grown at low temperature. Photocurrent spectra of the as-grown sample show a dip near 50–60 meV below the conduction edge for sample temperatures of 18–275 K. The magnitude of this dip is observed to be temperature dependent and one possible explanation of this new phenomenon is the trapping of electrons by arsenic vacancies. An annealed sample does not show this feature at any sample temperature.