Enhanced terahertz detection by localized surface plasma oscillations in a nanoscale unipolar diode

Abstract

By using a two-dimensional ensemble Monte Carlo method, we have studied the terahertz-frequency response of a self-switching device (SSD), which is a semiconductor rectifier consisting of an asymmetric nanochannel. The simulations reveal that the performance can be improved by adjusting the shape and dielectric material filling of the insulating trenches that define the SSD. We show that the rectified current of the SSD has a nonmonotonic frequency dependence with a pronounced peak occurring just below the cutoff frequency. Through optimizations of the geometry, the peak current can reach twice that at low frequencies, enabling not only a higher detection sensitivity but also a degree of frequency selectivity. The effect is discussed in terms of a localized surface plasma oscillation in the asymmetric nanostructure.

THz operation of asymmetric-nanochannel devices

“…The device, being both planar and requiring only a single lithographic step, is to our knowledge the simplest diode to date. Recently, Monte Carlo simulations predicted that the device could operate at frequencies up to a few THz (wavelength ∼ 100 μm) [14][15][16].…”

“…The simple treatment developed in [17] predicted for an SSD with a channel completely depleted by surface states a current proportional to the square of the applied voltage in forward bias over threshold, or zero otherwise, in very good agreement with the experiments. A more accurate description of the transport properties of SSDs, aided by Monte Carlo simulations, in both the AC and DC regimes, is in [14][15][16]18]. …”

Terahertz tunable detection in self-switching diodes based on high mobility semiconductors: InGaAs, InAs and InSb

“…The analysis of the current noise spectra calculated in SSDs made of InGaAs, InAs and InSb allows confirming the physical origin of such a peak, already explained in previous works [5][6]. The influence of decreasing temperature on the resonance features is also investigated as another possible improvement in device performance.…”

“…Origin of the resonance and noise spectra. The physical origin of the resonance was studied in previous works [5][6]. It is attributed to a collective charge fluctuation phenomenon (associated to returning carries [5] or localized surface plasma (LSP) effects [6]) in the space-charge region around the active channel of the device.…”

Enhanced Terahertz detection in self‐switching diodes

“…MC models have been proved to be quite useful for the analysis of the static, dynamic and noise behavior of SSDs [8,[11][12][13]. In this work we will analyze the high-frequency behavior of SSDs operating as detectors by means of MC simulations.…”