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High-conductivity 2D holes induced by polarization discontinuity in GaN/AlN

When an electrically-insulating material is grown on top of another insulator, the interface between the two insulators can be populated by mobile electrons. This has been achieved in interfaces that have a polarization discontinuity, such as AlGaN/GaN and LaAlO3/SrTiO3. It would be valuable to create a layer of mobile positive charges called holes, because electronic devices rely on charge carried by both electrons and holes.

A Cornell group’s discovery of high-conductivity holes at the interface between GaN and AlN completes the hunt for electrons and holes induced by polarization in the column III-nitride semiconductors. These materials have enabled solid-state lighting and highly-efficient microwave and power electronics. This finding creates a way to explore the physics of closed-packed high-density electron-hole systems in this technologically-relevant material system.

Difference in internal polarization fields at the metal-polar GaN/AlN interface gives rise to a negative sheet charge, which induces a layer of mobile positive holes– no chemical impurity doping is required. The resulting holes maintain their high densities at temperatures down to 10 degrees above absolute zero.
Difference in internal polarization fields at the metal-polar GaN/AlN interface gives rise to a negative sheet charge, which induces a layer of mobile positive holes– no chemical impurity doping is required. The resulting holes maintain their high densities at temperatures down to 10 degrees above absolute zero.
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