Stability of a low-temperature grown GaAs surface layer following air exposure using tunneling microscopy
نویسندگان
چکیده
The stability of a GaAs layer structure consisting of a thin ~10 nm! layer of low-temperature-grown GaAs on a heavily n-doped GaAs layer, both grown by molecular beam epitaxy, has been studied using a scanning tunneling microscope. The sample was exposed to the atmosphere between the layer growth and STM characterization. Tunneling spectroscopy shows both the GaAs band edges and a band of midgap states associated with the excess As in the surface layer. The observation of midgap states following atmospheric exposure indicates that the low-temperature-grown GaAs layer does not oxidize rapidly. The spectroscopy results are used to confirm a model for conduction in low resistance, nonalloyed contacts employing comparable layer structures. © 1996 American Institute of Physics. @S0003-6951~96!01716-8#
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