Terahertz harmonic generation using a planar nanoscale unipolar diode at zero bias

Abstract

The feasibility of harmonic generation in a planar nanoscale unipolar diode, called a self-switching device, is analyzed using a two-dimensional ensemble Monte Carlo method. A suitable channel width is chosen to enable a zero threshold voltage. The current-voltage and capacitance-voltage characteristics both demonstrate strong nonlinearity. It is shown that the noise of the device is below the shot noise level until about 1THz, after which two noise peaks arise. As such, a good signal-to-noise ratio can be achieved for up to six harmonics and beyond 1THz. The physical origins of the noise peaks are discussed.

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

“…Indeed, operations of the device up to 110 GHz have been observed in experiments 15 and speeds up to a few terahertz have been envisaged in Monte Carlo simulations. 14,16 A semiclassical EMC method self-consistently coupled with the Poisson equation is used in this work. 17 For an exact modeling of the devices, three-dimensional ͑3D͒ simulations would be necessary in order to take into account the effect of the lateral surface charges and the real topology of the structures.…”

“…It is also known that if the SSD is biased, the trench sidewalls will be charged either positively or negatively, which results in the electrostatic opening or closing of the nanochannel. 11,14 Hence, attentions are paid to the timedependent charging and discharging of the region close to the vertical trenches. In order to highlight the difference from the dc condition, the total charge changes obtained under terahertz cyclostationary conditions are normalized by using the following equation:…”

“…A more sophisticated model was also developed by using a self-consistent ensemble Monte Carlo ͑EMC͒ method, which enabled the studies of the detailed electron transport inside the nanochannel of the SSD. 13,14 In this work, we perform Monte Carlo simulations to focus on the frequency-dependent and time-dependent responses of the SSD under different structural parameters. The frequency-dependent simulations show that the rectified current and cutoff frequency of the device can be improved by adjusting the shape and dielectric material filling of the insulating trenches that define the nanochannel of the SSD.…”

Enhanced Terahertz detection in self‐switching diodes

“…In previous works [11,12] the MC analysis of the current noise spectral density in SSDs has evidenced the presence of a peak with a dependence on W v analogous to that observed in the case of the rectifying response. To identify the similarities, in Figure 7 we compare the frequency dependence of the current noise spectral density S I (f) (calculated at equilibrium) with that of the DC rectified current in SSDs with different W v .…”

“…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.…”