Fabrication of ultrahigh resolution structures in compound semiconductor heterostructures

Techniques have been developed to make silicon metal-oxide-semiconductor field-effect transistor (MOSFETs) with minimum dimensions as small as 25 nm for fundamental electron transport studies. These devices have been used to study a variety of quantum conduction and electron scattering effects. At a given size scale, these quantum effects can be increased by replacing silicon in these devices with a high mobility, low electron mass semiconductor like GaAs. To make such devices, we have extended our technology to the fabrication of III–V semiconductor nanostructures. As an example of this, we describe the fabrication of 0.1 μm rings in modulation-doped GaAs using electron beam lithography and reactive-ion etching.