NANOLITHOGRAPHY ON III-V-SEMICONDUCTOR SURFACES USING A SCANNING TUNNELING MICROSCOPE OPERATING IN AIR

Nanometer-scale pattern generation on III-V semiconductor substrates using a scanning tunneling microscope (STM) operating in air is demonstrated. The sample substrates, consisting of arsenic-capped, epitaxial layers of n-doped GaAs, AlxGa1-xAs and InyGa1-yAs were prepared by molecular beam epitaxy and characterized by time-of-flight secondary-ion mass spectrometry and x-ray photoelectron spectroscopy. The direct patterning of features of width less-than-or-equal-to 50 nm on GaAs and In0.2Ga0.8As surfaces is shown to be the result of the formation of a strongly bonded surface oxide induced under high electric field conditions existing between the scan tip and the substrate. The significance of STM pattern generation of nanometer-scale oxide masks for use in the fabrication of low-dimensional heterostructures is discussed.