Inhomogeneity-mediated systematic reduction of the Schottky barrier in a Au/GaN nanorod film interface

Self-aligned GaN nanorods of various densities are grown on an r-plane Al2O3 substrate with Stranski-Krastanov or layer-plus-island growth conditions by using a plasma-assisted molecular beam epitaxy system. These conditions result in the formation of a GaN nanorod matrix on an epitaxial GaN thin film. The orientation of the nanorods was found to be at an inclination of similar to 60 degrees from the substrate. As expected, the GaN thin film grows along the [11-20] direction, but interestingly the nanorods have a preferential growth direction along the [0002] axis. The overall structure mimics the Gaussian distribution of Schottky barriers at the metal-semiconductor interface. The GaN nanorod/thin-film matrix systematically causes the well-known Au/GaN Schottky metal-semiconductor interface to display an Ohmic type of behavior. A systematic reduction of the Schottky barrier is observed with an increase in the GaN nanorod density (from 5 to 65 nanorods micron(-2)). The overall configuration provides a tunable Gaussian distribution of Schottky barriers with nanorod density, which could be extremely useful for replacing conventional multi-level electrode stacking techniques.

Automated summary

Self-aligned GaN nanorods of various densities are grown on an r-plane Al2O3 substrate using a plasma-assisted molecular beam epitaxy system. The nanorods have an inclination of 60 degrees from the substrate, while the GaN thin film grows along the [11-20] direction and nanorods preferentially grow along the [0002] axis, mimicking the Gaussian distribution of Schottky barriers. Increasing the GaN nanorod density results in a systematic reduction of the Schottky barrier, providing a tunable Gaussian distribution of Schottky barriers suitable for replacing conventional multi-level electrode stacking techniques.