A Study of the Transition from High to Low-Resistivity in As-Grown GaAs MBE Material

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This work discusses the transition from high resistivity as-grown GaAs layers to thermally metastable low resistivity as-grown layers by molecular beam epitaxy. This transition occurs at about 430 degrees C and coincides with a reflective high energy electron diffraction reconstruction change from a 2 x 1 to 2 x 4 pattern for an As-4/Ga beam equivalent pressure ratio of 20. For growth temperatures in the range 350 to 430 degrees C, room temperature Hall-effect measurements have shown resistivities of >10(7) ohm-cm and photoluminescence has shown new peaks at 0.747 eV and a band from 0.708 to 0.716 eV at 4.2K, in unannealed material.