RESONANT-TUNNELING DIODE, RTD (REFERENCE: CANON NEW PRODUCT INTRODUCTION)

Double Barrier Energy Band Diagram (eV on vertical axis) from:

Results in Physics

Volume 17, June 2020, 103089

Results in Physics

Theoretical study of electronic properties of resonant tunneling diodes based on double and triple AlGaAs barriers

Shaffa Almansour

Resonant-tunneling Diode

LINK TO KYOCERA WEB PAGE FEATURING CANON RTD, WITH SOME ADDITIONAL COMMENTS:

https://www.dhirubhai.net/posts/greg-merrell-28234262_%E3%82%AD%E3%83%A4%E3%83%8E%E3%83%B3%E6%A0%AA%E5%BC%8F%E4%BC%9A%E7%A4%BE%E6%A7%98%E3%83%86%E3%83%A9%E3%83%98%E3%83%AB%E3%83%84%E3%83%87%E3%83%90%E3%82%A4%E3%82%B9-%E3%82%BB%E3%83%A9%E3%83%9F%E3%83%83%E3%82%AF%E3%83%91%E3%83%83%E3%82%B1%E3%83%BC%E3%82%B8-%E4%BA%AC%E3%82%BB%E3%83%A9-activity-7265223856586395649-pzYO?utm_source=share&utm_medium=member_desktop

The RTD is a specialized semiconductor diode which operates due to quantum mechanical effects, and is a subject of study in solid state physics. Canon has introduced a new RTD recently, and has described it on-line through Kyocera. This article is a result of some searches due to curiosity about the RTD, its operation, and its application to 6G-type frequencies.

An RTD exhibits a negative-resistance current vs. voltage characteristic that allows it to generate or amplify signals. The frequency range for this is roughly 1 THz, just below optical fiber/infrared frequencies. The term “roughly” is an understatement as the THz range is 0.1 THz to 10 THz, two orders of magnitude in frequency.

The following information has been obtained through AI-assisted internet search:

RTD’s vs. Gunn diodes:

A resonant-tunneling diode (RTD) operates based on quantum mechanical principles, utilizing a double-barrier structure to achieve negative differential resistance (NDR) through resonant tunneling, while a Gunn diode depends on the transfer of electrons between different energy valleys in a semiconductor material to produce NDR, making it primarily useful for high-frequency microwave generation; essentially, RTDs are more focused on precise control of electron energy levels for high-speed applications, whereas Gunn diodes are designed for high-power microwave generation at specific frequencies.

Key Differences:

Mechanism:

RTDs utilize quantum tunneling through a precisely engineered double-barrier structure, while Gunn diodes use the "transfer-electron effect" where electrons move between different energy valleys in the semiconductor material.

Structure:

RTDs have a complex layered structure with very thin quantum wells, whereas Gunn diodes are typically simpler, consisting of a single semiconductor material with specific doping profiles.

Applications:

RTDs are primarily used in high-speed electronics like logic circuits and terahertz devices due to their fast switching capabilities, while Gunn diodes are mainly employed in microwave oscillators and amplifiers due to their ability to generate high-frequency signals.

Negative Differential Resistance (NDR):

Both devices exhibit NDR, but in RTDs, the NDR is highly localized around specific voltage points due to the resonant tunneling effect, whereas in Gunn diodes, the NDR is more broadly distributed across a voltage range.

RTD vs. Tunnel (Esaki) Diode:

A tunnel diode is a basic semiconductor diode that utilizes quantum tunneling through a heavily doped p-n junction, while a resonant tunneling diode (RTD) is a more complex structure with a double-barrier quantum well, allowing for more precise control over the tunneling process, resulting in distinct peaks in its current-voltage characteristics and potentially higher operating frequencies; both exhibit negative differential resistance, but RTDs offer greater potential for high-speed applications due to their quantum well design.

Key Differences:

Structure:

A tunnel diode has a simple heavily doped p-n junction, while an RTD has a double-barrier quantum well structure.

Tunneling Mechanism:

In a tunnel diode, tunneling occurs due to the overlap of valence and conduction bands, while in an RTD, tunneling is highly dependent on the energy levels within the quantum well, creating resonant peaks in the current-voltage curve.

Applications:

Tunnel diodes are often used in high-frequency applications due to their fast switching speed, while RTDs are being explored for ultra-high-speed electronics and terahertz oscillators due to their precise control over tunneling. Tunnel diodes are often used for microwave signal detection.

Materials:

RTD’s and Tunnel (Esaki) Diodes: Germanium, Silicon, Gallium Arsenide, Indium Phosphide.

Gunn Diodes: Gallium Arsenide, Indium Phosphide, Gallium Nitride (III-V materials).

Years of invention:

Gunn Diode: 1963 J.B. Gunn

Tunnel Diode: 1957 Leo Esaki and Yuriko Kurose

Resonant-tunneling Diode: 1973 Tsu and Esaki

The material described in the Kyocera web page for the Canon device is Indium Phosphide, mounted in a Kyocera ceramic package.

Some additional resources:

https://global.canon/ja/technology/terahertz-device-2023.html

https://www.sciencedirect.com/topics/physics-and-astronomy/resonant-tunneling-diodes

From Tokyo Institute of Technology:

https://iopscience.iop.org/article/10.35848/1882-0786/ad5c27

Basic Theory and Application of Tunnel Diodes

By Sylvester P. Gentile · 1962 Publisher: Van Nostrand