New Insight on Terahertz Rectification in a Metal–Oxide–Semiconductor Field-Effect Transistor Structure

Fabrizio Palma

doi:10.3390/electronics9071089

Abstract

The use of a metal–oxide–semiconductor field-effect transistor (MOS-FET) permits the rectification of electromagnetic radiation by employing integrated circuit technology. However, obtaining a high-efficiency rectification device requires the assessment of a physical model capable of providing a qualitative and quantitative explanation of the processes involved. For a long time, high-frequency detection based on MOS technology was explained using plasma wave detection theory. In this paper, we review the rectification mechanism in light of high-frequency numerical simulations, showing features never examined until now. The results achieved substantially change our understanding of terahertz (THz) rectification in semiconductors, and can be interpreted by the model based on the self-mixing process in the device substrate, providing a new and essential tool for designing this type of detector.

Highlights

The terahertz (THz) radiation spectrum covers the gap between microwaves and infrared regions.Since THz radiation is non-ionizing and the associated power is low, it is considered medically safe
Using technology computer-aided design (TCAD), we show that rectification photovoltage arises mainly in the depleted region under the gate oxide, confirming the one-dimensional model prediction
The two-dimensional nature of the TCAD analysis permits us to evaluate how the charge displacement generated by the self-mixing effect, dielectrically coupling toward the doped regions under the contacts, can be held as the origin of the transient currents detected in several measurements performed on metal–oxide–semiconductor field-effect transistor (MOS-FET) at

Summary

Introduction

The terahertz (THz) radiation spectrum covers the gap between microwaves and infrared regions. Combining all these characteristics could allow the realization of detector arrays up to whole panel scale, achieving a wide area detection approach In this scenario, a reliable model of the structure taking into account the rectification process is necessary for proper support of detector design. A new approach was developed, referred to as a self-mixing model in the substrate, showing how the presence of an RF electric field in a depletion region of a semiconductor can produce DC photovoltage This result was first achieved in studying a double barrier structure [11], was extended to the single barrier present in a unidimensional MOS structure in the depletion condition [12]. This approach allows us to highlight features never examined until now, shedding new light on the mechanisms of rectification

Analytical Interpretation and Numerical Simulator

Simulation of THz Rectification in MOS-FET Structure

Self-Mixing Effects Iside the Silicon Structure

Rectification Effects at the Contacts

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Conclusions