Room-Temperature Terahertz Detectors Based on Semiconductor Nanowire Field-Effect Transistors

Abstract

The growth of semiconductor nanowires (NWs) has recently opened new paths to silicon integration of device families such as light-emitting diodes, high-efficiency photovoltaics, or high-responsivity photodetectors. It is also offering a wealth of new approaches for the development of a future generation of nanoelectronic devices. Here we demonstrate that semiconductor nanowires can also be used as building blocks for the realization of high-sensitivity terahertz detectors based on a 1D field-effect transistor configuration. 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 nonlinearity of the transfer characteristics: the terahertz radiation field is fed at the gate-source electrodes with wide band antennas, and the rectified signal is then read at the output in the form of a DC drain voltage. Significant responsivity values (>1 V/W) at 0.3 THz have been obtained with noise equivalent powers (NEP) < 2 × 10(-9) W/(Hz)(1/2) at room temperature. The large existing margins for technology improvements, the scalability to higher frequencies, and the possibility of realizing multipixel arrays, make these devices highly competitive as a future solution for terahertz detection.

One dimensional semiconductor nanostructures: An effective active-material for terahertz detection

“…Such a performance is almost independent from the antenna configuration. Either a simple bow-tie 24 or a metamaterial-resonant antenna 25 indeed gave comparable responsivities when patterned asymmetrically between G and S. In agreement with previous reports, 21 no signal was detected in similar devices exploiting identical antennas patterned symmetrically between source and drain, ruling out any effect related to temperature changes or to nonlinearity of the contact junctions. Figure 3 shows the 3D plot of the angle-resolved and frequency resolved responsivity of device A.…”

“…Taking into account that the total detector area is smaller than the diffraction limited one, the active area is taken equal to S λ = λ 2 /4; besides this, the beam spot area is given by S t = πd 2 /4 and P a = P t ·(S λ /S t ) = 7.1-5.6 µW. 21 The photoinduced source-drain voltage ∆u was measured at the D contact, while keeping V sd = 0 and S grounded, with a lock-in amplifier (LIA) connected to a low-noise voltage preamplifier having an input impedance of 10 MΩ and an amplification factor G n = 25. ∆u can be therefore estimated from the signal measured by the LIA as ∆u = 2.2·(LIA)/G n , where the factor 2.2 takes into account that the lock-in gives the rms of the fundamental sine wave Fourier component of the square wave produced by the chopper.…”

“…As an example, photoemissive detectors based on AlGaAs and GaSb structures or GaAs/AlGaAs modulation doped structures have been proposed and realized although with quite low quantum efficiencies in the THz; 12 also, photothermoelectric detectors based on carbon nanotubes embedded in a p-n junction were successfully implemented with reasonably high responsivity (a few V/W) in the ν > 1 THz frequency range. 17 We recently proposed 2D-or 1D-FETs based on graphene [18][19][20] or semiconductor nanowires (NWs) [21][22][23][24][25] as a low-noise, high speed, and high efficiency detection technology across the THz band. Our architecture strategy is based on the possibility to engineer the channel of a FET as a resonator for plasma waves, whose frequency can be properly tailored across the THz: gated regions hundreds-nm wide can indeed support propagation of collective density oscillations (plasma waves) at THz frequencies.…”

“…[21][22][23][24] InAs NWs, with narrow bandgap and degenerate Fermi-level pinning, revealed to be a successful material choice for preserving good detecting performances while scaling down the dimension of the device to increase the detected frequency up to the 1.5-3 THz range, accessible with QCL sources. 22 In this paper, we report on our recent progresses in engineering 1D NW FETs exploiting novel materials combinations and/or geometries to address simplified architectures and fast response times, beneficial for addressing the goal of a semiconductor plasma wave detector array technology.…”

“…2(a). Such an approach has been successfully exploited to develop THz FET detectors in the overdamped plasma wave regime, operating between 0.3 and 1.5 THz with responsivities up to ≈12 V/W and noise equivalent powers NEP = 6 × 10 −11 W/ √ Hz by employing either bow-tie 22 or log-periodic, 21 antennas. The lower bound of the spectral band of such antennas corresponds to a wavelength that is twice the overall antenna length.…”