Standard semiconductor processing uses ultraviolet light, which is capable of fabricating features down to the 0.2 micron level. To make smaller devices we must use radiation with a shorter wavelength, such as electron beams. The Semiconductor Nanofabrication Facility at UNSW houses complete facilities for processing both silicon and and gallium arsenide devices. In particular a Leica EBL100 lithography system allows fabrication of devices smaller than 0.02 microns.

Using electron beam lithography it is possible to fabricate a pair of gate electrodes above a two-dimensional electron system contained in a HEMT (shown above). A small sub-micron gap is left between the electrons which can be used to define a one-dimensional channel. Applying a small negative voltage to these split-gate electrodes repels electrons beneath the gates, creating a narrow constriction that connects the two sides of the device (light blue region above). If the semiconductor device is of high enough quality that electrons can travel along this narrow channel without scattering, then the channel acts as a one-dimensional electron waveguide.

Making the gate voltage more negative squeezes the one dimensional channel, which gradually becomes narrower.  At low temperatures the conductance G (G=1/R) of the quantum wire decreases in quantised steps, as the number of modes in this one-dimensional waveguide is decreased.

The flexibility of electron beam lithography also makes it possible to produce zero dimensional quantum boxes, and single electron transistors in which effects associated with the movement of individual electrons can be observed. single electron transistors are also used as extremely sensitive electrometers, and have significant applications for the development of solid state quantum computers.

MBE crystal growth
Using Molecular Beam Epitaxy it is possible to grow extremely pure single crystal semiconductor structures with atomic precision. moreover different semiconductors can be grown on top of each other, allowing band structure engineering.

The 2D Electron Gas
A 2D electron system is formed In a High Electron Mobility Transistor at the interface between gallium- arsenide and aluminium- gallium- arsenide.

Ultra-violet lithography
This UV lithography system at UNSW's Semiconductor Nanofabrication Facility can produce devices with features down to a few microns.

Electron Beam Lithography
This Leica EBL-100 system at the SNF can produces devices with features smaller than 25nm.