Gated Bow-Tie Diode for Microwave to Sub-Terahertz Detection.

Steponas Ašmontas,Aurimas Čerškus,Edmundas Širmulis,Algirdas Sužiedėlis,Maksimas Anbinderis,Vladimir Umansky,Jonas Gradauskas,Aldis Šilėnas

doi:10.3390/s20030829

Abstract

We propose a new design microwave radiation sensor based on a selectively doped semiconductor structure of asymmetrical shape (so-called bow-tie diode). The novelty of the design comes down to the gating of the active layer of the diode above different regions of the two-dimensional electron channel. The gate influences the sensing properties of the bow-tie diode depending on the nature of voltage detected across the ungated one as well as on the location of the gate in regard to the diode contacts. When the gate is located by the wide contact, the voltage sensitivity increases ten times as compared to the case of the ungated diode, and the detected voltage holds the same polarity of the thermoelectric electromotive force of hot electrons in an asymmetrically shaped n-n+ junction. Another remarkable effect of the gate placed by the wide contact is weak dependence of the detected voltage on frequency which makes such a microwave diode to be a proper candidate for the detection of electromagnetic radiation in the microwave and sub-terahertz frequency range. When the gate is situated beside the narrow contact, the two orders of sensitivity magnitude increase are valid in the microwaves but the voltage sensitivity is strongly frequency-dependent for higher frequencies.

Highlights

Ability of microwave (MW) and terahertz (THz) radiation to penetrate through a low conductivity medium and atmosphere makes it very attractive to be used in many fields, such as high-speed wireless communications [1,2,3], detection of concealed objects [4,5], medicine [6,7], materials science [8,9], and large area imaging [10,11]
It is essential to note that the nonlinear properties of plasma waves in a transistor channel make it possible to detect radiation at frequencies substantially higher than the transistor cut-off frequency since the plasma wave velocity is much higher than the drift velocity of two-dimensional electrons in the transistor channel [21]
Results and Discussion had polarity of the thermoelectric force of hot electrons, positive potential was Voltage signal detected across theelectromotive ungated bow-tie diode located on the i.e., semiconductor substrate induced on the narrow contact of the diode

Summary

Introduction

Ability of microwave (MW) and terahertz (THz) radiation to penetrate through a low conductivity medium and atmosphere makes it very attractive to be used in many fields, such as high-speed wireless communications [1,2,3], detection of concealed objects [4,5], medicine [6,7], materials science [8,9], and large area imaging [10,11]. A field-effect transistor biased by the gate-to-source voltage and subjected to electromagnetic radiation can produce a dc drain-to-source voltage which has a resonant dependence on radiation frequency ω with a maximum point at plasma oscillation frequency ωo [14,21]. When ωo τi >> 1, the field-effect transistor operates as aω representing a non-resonant detection. Of Spectral measurements its up voltage showed it to be nearly independent tie diode is based on non-uniform electron heating effects arising due to the specific shape and doping of the frequency from 10 GHz up to 0.7 THz [25,26]. It should be noted that all bow-tie diodes have demonstrated lower voltage sensitivity than the concealed low-absorbing objects field-effect transistors. The investigation was carried out within the GHz-subTHz frequency range

Samples and Measurement Technique

The gate beside beside the the neck neck of of the the diode diode

Results and Discussion

Dependence of the detected voltage on blue

Conclusions