|Room Temperature Terahertz detectors based on semiconductor nanowire field effect transistors |
Conference: Conference on Quantum Sensing and Nanophotonic Devices IX (San Francisco (CA), FR, 2012-01-22)
Self-assembled nanowires represent a new interesting technology to be explored in order to increase the cut-off frequency of electronic THz detectors. They can be developed in field effect transistor (FET) and diode geometries exploiting non-linearities of either the transconductance or the current-voltage characteristic as detection mechanism. In this work we demonstrate that semiconductor nanowires can be used as building blocks for the realization of high-sensitivity terahertz one-dimensional FET detectors. In order to take advantage of the low effective mass and high mobilities achievable in III-V compounds, we have used InAs nanowires, grown by vapor-phase epitaxy, and properly doped with selenium to control the charge density and to optimize source-drain and contact resistance. The detection mechanism exploits the non-linearity of the transconductance: the THz radiation field is fed at the gate-source electrodes with wide band antennas, and the rectified signal is then read at the drain output in the form of a DC voltage. Responsivity values as large as 1 V/W at 0.3 THz have been obtained, with noise equivalent powers (NEP) < 2 x 10(-9) W/root Hz at room temperature. The large existing margins for technology improvements, the scalability to higher frequencies, and the possibility of realizing multi-pixel arrays, make these devices highly competitive as a future solution for THz detection.