Electron transport in GaN/AlGaN heterostructure
Contact Hung-Tao Chou (hungtao@) for more information.
Advanced semiconductor processing now offers
physicists a powerful tool to design and fabricate mesoscopic structures at the nanoscale.
Using this technology, we study electron transport at
the quantum regime to probe the quantum state. Almost all mesoscopic
experiments up to now have been done in GaAs/AlGaAs heterostructures.
Because of its clean interfaces with good lattice match and mature growth
and process technologies, electrons transport in this system is usually
treated as material independent and similar to electrons moving in vacuum.
But when there are puzzles hard to understand such as 0.7 structure in
quantum point contacts [1,2], performing experiments on another material
with different properties would provide a direct comparison and offer us a
more insightful understanding of the physics.
We have fabricated the first quantum point contact in a GaN/AlGaN heterostructure (above) and observed clear quantized conductance plateaus and 0.7 structure (below) . An effective g-factor of 2.5 is also measured from the spin-split plateau at high magnetic field. We are now trying to study the 0.7 structure in GaN quantum point contacts more carefully and also fabricate more advanced mesoscopic structure such as quantum dots.
 K. J.
Thomas, J. T. Nicholls, M. Y. Simmons, M. Pepper, D. R. Mace, and D. A.
Ritchie, Phys. Rev. Lett. 77, 135 (1996).