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Oxidation behavior with quantum dots formation from amorphous GaAs thin films

ABSTRACT We investigated the oxidation behaviour of an amorphous GaAs thin film deposited onto a micro/nanotextured Si surface by an electron beam. After the deposited film was exposed to air, microcrystallites were formed with octahedral cubic and monoclinic structures of arsenic oxides. Short time exposure after thin film deposition showed the formation of cubic arsenolite while long time exposure showed the formation of monoclinic claudetites as well as cubic arsenolites. These oxide microcrystallites at the GaAs thin film surface disappeared after the sample annealing process. However, the amorphous GaAs thin film included high-density GaAs nanodots. From UV and inverse photoemission spectroscopies, the thin film showed n-type band structure with an energy gap of 2.73 eV. Photoluminescence measurement showed an emission peak at (450–513) nm with the energy of (2.41–2.75) eV corresponding to dot size of (4.1–4.5) nm.