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

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.

Competition between Direct Detection Mechanisms in Planar Bow-Tie Microwave Diodes on the Base of InAlAs/InGaAs/InAlAs Heterostructures

“…They are similar; however, this is most probably not due to the properties of the W-diode itself but rather the features of the microwave signal transmitting tract, specifically the high-frequency probe station. The experimental frequency dependence of the voltage sensitivity of the W-diode in the dark can be compared with the theoretical voltage sensitivity of the bow-tie diode with the semiconductor n-n + junction [ 44 ]: where P is the microwave power absorbed by the diode; P i denotes the incident microwave power; μ 0 is the low-field electron mobility; and N stands for the factor that depends on the frequency and electron energy, pulse and the Maxwell relaxation times [ 44 ]. The calculated frequency dependence of the voltage sensitivity of the W bow-tie diode with the electrical and geometrical parameters is presented in Figure 10 as a line.…”

Sensitive Planar Microwave Diode on the Base of Ternary AlxGa1-xAs Semiconductor Compound

“…These bow-tie diodes were successfully used for heterodyne and spectroscopic terahertz imaging and sensing [ 22 , 23 ]. Low-voltage responsivity was the main drawback of the bow-tie diode; it was increased by means of partial gating of the active two-dimensional electron gas layer in the vicinity of the diode’s contacts [ 24 ]. Another kind of microwave diodes having the active region situated in the bulk of a device is the heterojunction diode.…”

Hot Carrier Photocurrent through MOS Structure

“…Thus, the hot carrier effect attracts interest not only from the fundamental point of view but it also finds a lot of applications. For example, it is employed in the detection of microwave [9,10] and infrared radiation [11], and even within the whole region between both these ranges including the THz frequencies [12,13]. In addition, the concept of hot carrier solar cell as remained an important focus of research topics during the last several decades [14][15][16].…”