Skip to main content

MIM & MIIM Diodes: How Do They Work?

What drains power in today’s electronics, what causes high temperatures and costs in today’s electronic equipment, could be behind extreme electronics of tomorrow. Our world is gearing towards a better tomorrow, where the supercomputers will be millions of times faster than today’s. Processing will be remarkably faster, and high level applications will run in nanoseconds.

What will help us achieve this for our future? The technology known as MIM diodes and its successor, MIIM diodes (Metal-Insulator-Insulator-Metal diodes). Let’s check them out in detail.

What Is MIM & MIIM?


diodesA diode is one of the most basic electronic components of any circuit. It is used to conduct electrons in one direction, like a valve. Advanced diodes are capable of modifying the current as well, such as sine wave to square wave, AC to DC, etc.

Diode is such an important component in today’s electronics that without them nothing would be possible—no cellphones, tablets, PCs, display technologies, speakers, storage systems, servers, clients, automobiles, or anything.

These electronic components—diodes, transistors, ICs, etc.—are developed with some kind of semiconductor, and the most widely used of them is Silicon. Other semiconductors are also there, such as Germanium, Gallium Arsenide, and certain organic semiconductors. However, Silicon is the one major semiconducting material we use in all kinds of electronic equipment.

Today’s technologies, however, are pushing the limits of what Silicon-based diodes and ICs can achieve in terms of speed and performance. In a world like that, a better technology that transforms electronics as we know it today is the prime solution. A research to find such a solution resulted in further developing an already existing technology, MIM diodes.

MIM stands for Metal-Insulator-Metal diodes. These are sort of like capacitors in which thin metal plates are separated by an insulator. Here’s the basic structure of a MIM diode. See how the insulator separates metal strips.

MIM diode structure

Oregon State University (OSU) has been working on MIM diodes for such a long time. In 2011, there was a paper published by researchers in this particular area.



Douglas KeszlerIn 2010, OSU finally managed to create the first ever MIM diode. Douglas Keszler, chemist and one of the leading materials science researchers from OSU, said then:
Researchers have been trying to do this for decades, until now without success. Diodes made previously with other approaches always had poor yield and performance. It’s a basic way to eliminate the current speed limitations of electrons that have to move through materials.


Here’s the first ever MIM Diode:

first MIM diode

Now, OSU has gone further and created the next level of MIM, MIIM diodes. Here, instead of a layer of insulator, there are two.

Here’s an image. The material has four layers—ZCAN (Amorphous Zirconium), Hafnium Oxide (HfO2), Aluminum Oxide (Al2O3), and Aluminum (Al).

MIIM diode

As I mentioned earlier, the technology is not new. The MIIM diodes are a type of ‘tunnel diodes’ that were in existence since the 60’s, known for the technology behind it, ‘quantum tunneling’. It has never been researched further and developed for mass production.

SanDisk 3D LLC, a subsidiary of the flash storage memory maker, SanDisk, has a patent on MIIM diodes with a trench structure. The patent dates back to 2008, although no work has been done by the company based on the technology.

What Is Quantum Tunneling?


Quantum Tunneling is the technology behind MIM diodes. As we mentioned, the tunnel diodes are called so due to this reason.

Normally, we know an electron beam is unable to go through an insulator. However, when the insulating material is extremely thin at less than 3 nm, a special phenomenon known as quantum tunneling can happen. This phenomenon can only be explained with quantum mechanics, not classical mechanics. This is the reason why it is known as ‘quantum tunneling’. This concept has a more extensive reach than MIM diodes. For instance, the energy production in the Sun actually has a lot to do with quantum tunneling.

Imagine a ball rolling up a hill. It will not be able to cross the hill if the energy it already has is not enough. However, if you are thinking of a ball in the quantum scale (which is infinitesimal), the ball can no longer be regarded as an object, but as a wave. In such a state, it can be expected that the ball crosses to the other side of the said hill if the other side has a slope where the ball can stay without expending much energy.

The same concept applies to electrons in MIM diodes. When the electron reaches the barrier, the insulator in between the metal strips, it absorbs energy from the surroundings in order to pass through the insulator. In doing that, a part of the electron beam passes through the barrier, but another part reflects back. However, due to the energy absorption, the reflected electron beam has far more energy than it originally has.

quantum tunneling with electrons

The electron beam that traverses the barrier does not follow the normal laws of conduction as it is going through an insulator, which does not help in conducting electrons. Due to this reason, the energy the beam absorbs makes it travel at ultra-high speeds. The speed is much higher than that on a normal conductor or a semiconductor like Silicon.

Also, when we visualize electron beam as a wave, quantum tunneling can be seen in action below. Quantum tunneling happens in the form of a ripple effect you see at the barrier. Also, after that, the passing beam and the reflected beam have lower altitude (height) and higher wavelength.

Quantum tunneling visualization

This tunneling phenomenon is what causes the extreme speed on MIM and MIIM diodes.
Ironically enough, as mentioned at the beginning of the article, quantum tunneling is a major reason behind power drain and extreme temperature in current electronic systems, but that is unwanted quantum tunneling.


John Conley Jr.

Extra insulator layer helps enhance an MIM diode. Dr. John Conley, Jr.,  of OSU that was part of the research into MIIM says:

This approach enables us to enhance device operation. It ... moves us closer to the real applications that should be possible with this technology.



This extra insulator layer causes something known as ‘step tunneling’ that allows highly precise control of the asymmetric diodes.

Advantages


Quantum tunneling and MIIM diodes have only advantages.
  • They are as easy to manufacture as Silicon based electronic components.
  • They are inexpensive.
  • They can form extremely fast electronic components as compared to any available technology today—imagine terahertz of processing power in place of gigahertz we have now.
  • They will find application in all kinds of electronic technologies—smartphones, tablets, LCD displays, TVs, consumer electronics, automobiles, etc.

Conclusion


I am not an electronics expert, but when it comes to technologies that will enhance what we have today in smartphones and tablets, I do take high level of interest. We do not have infrastructure today to make MIIM diodes on large scale. However, when it happens in the near future, we will all have extremely powerful smartphones and tablets. We will have in our hands devices better than the biggest and the most massive of today’s supercomputers.

[Image source: BSN, Wikipedia]

Popular posts from this blog

What Is the Role of a Firewall, and How Does It Secure a Network From Unsafe Traffic?

To understand firewalls, basic understanding of how networks function is requisite. Deep down, how do the packets of information that you send reach the intended receivers? How do the messages intended for you reach you safely? And how does it all function like clockwork? Let’s understand the basics of firewalls and see how a firewall secures the traffic in and out of a network. Consider this scenario for getting an understanding of how firewalls work. Say, you open up your browser to book a flight ticket for your upcoming vacation, and your computer is conveniently insecure without a firewall. Let’s say you come across an intriguing email that gives an offer you can’t refuse. You open the email and click a link, and bam! An unwanted piece of spyware is installed on your system. The spyware then proceeds to sit on your system tray, hidden from your eyes, tracking the keystrokes you make, reading the top-secret files you have, and looking for potentially rewarding information, such...

How to Send Email in Your Own Language Script Through Gmail?

Have you ever had trouble sending an email to a distant relative who speaks a different language altogether? It has never been easy on email applications to send messages in other languages. Google’s popular email service, Gmail has come up with transliteration tools and other language input tools to make the service much better. You can type using Gmail interface in any language that you want. First of all, you need to select the languages that you want to use in composer. For this, go to Gmail settings and you will see the ‘Language’ option under General. Here, go to advanced language options and put a check mark to ‘Enable input tools’. Here, you can transliterate (type in English the words in other languages to have them appear in correct script), use a virtual keyboard, or edit your input method with the help of a regular keyboard to convert words into other alphabet. Transliteration feature was available although limited in Gmail. Select the input tools from the list by d...

Digital Marketing Done Properly in the New Age

I suppose it’s coincidence that this post appears almost exactly one year after Blue Bugle went sort of inactive. Today, the blog doesn’t enjoy as many readers as it once used to. This unfortunate thing is due to my hectic schedule in my new day job as senior content writer for an organization called MSys. This job gives me more opportunities to explore the separate aspects of the digital marketing domain. In the past, all we used to do was promoting our blog posts through social media at random thereby trying to gather as many visitors as possible. You never studied the prospects, the market, or the social channels you promote your stuff to.  Most of the SEO companies out there prided themselves in creating spammy blog comments to create links to client websites. Needless to say, most of these plans never worked or had less positive impact. Now, if you follow the same spammy activities, you are sure to get a ban at best. I had to come up with a new marketing plan for MSys th...