The circuit of the Single-Electron Transistor as a charge sensor is shown in Fig. 1. It is fabricated
using the Electron Beam Lithography (EBL) exposure ure and angular deposition of Al at the top
of GaAs/AlGaAs heterostructure. Sketch the pattern of the EBL exposure used for this circuit.
After exposure and development the shadow evaporation technique of Al with two angles, +12°,
is used. The scale is shown in Fig.1.
1. Make a sketch of exposure pattern of the device. [10]
2. Estimate thickness of the resist used in the processing.[10]
3. Which technology, with a single or double layer resist, would you use for fabrication of the
SET circuit?[2]
4. Which method should be used for deposition of the Al when fabricating the circuit?[3]
QD gate
1
Quantum
Point
Contact
Tunnel
Junction
Quantum
Dot
SET
Quantum
Point
Contact
70nm
Figure 0.1: Scanning-electron micrograph of the Al pattern on a GaAs/AlGaAs heterostructure,
with a 2DEG 100 nm below the surface, used for a charge sensing experiment.