Three-dimensional shaping of sub-micron GaAs Schottky junctions for zero-bias terahertz rectification

We demonstrate a rectification mechanism based on quantum tunneling through the narrow Schottky barrier of a sub-micrometric Au/Ti/n-GaAs junction, which is capable of efficient power detection of free-space terahertz radiation beams even without an applied dc bias. Three-dimensional shaping of the junction geometry provides an enhanced zero-bias tunneling probability due to increased electric fields at the junction, resulting in cutoff frequencies up to 0.55 THz, responsivity up to 200 V/W, and noise equivalent power better than 10(-9) W/Hz(0.5) without applied dc bias. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3672439]