Probing and modelling the localized self-mixing in a GaN/AlGaN field-effect terahertz detector

TL;DR

This paper investigates the localized self-mixing effect in a GaN/AlGaN terahertz detector, demonstrating tunable photocurrent polarity and magnitude, and introduces a quasistatic model to describe these phenomena, emphasizing the importance of spatial field engineering.

Contribution

It presents a quasistatic self-mixing model for a GaN/AlGaN terahertz detector that accounts for localized fields and explains the tunable photocurrent behavior.

Findings

Photocurrent polarity and magnitude can be tuned via gate voltage and bias.

Localized terahertz fields significantly influence detector response.

A quasistatic model accurately describes the localized self-mixing effects.

Abstract

In a GaN/AlGaN field-effect terahertz detector, the directional photocurrent is mapped in the two-dimensional space of the gate voltage and the drain/source bias. It is found that not only the magnitude, but also the polarity, of the photocurrent can be tuned. A quasistatic self-mixing model taking into account the localized terahertz field provides a quantitative description of the detector characteristics. Strongly localized self-mixing is confirmed. It is therefore important to engineer the spatial distribution of the terahertz field and its coupling to the field-effect channel on the sub-micron scale.