We are independent & ad-supported. We may earn a commission for purchases made through our links.
Advertiser Disclosure
Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.
How We Make Money
We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently of our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is a Planar Transistor?

By C.B. Fox
Updated May 16, 2024
Our promise to you
EasyTechJunkie is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At EasyTechJunkie, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject-matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

The planar transistor was invented by Jean Hoerni in 1959. The design of the planar transistor improved on earlier designs by making them cheaper to make, mass-producible, and better at amplifying electrical input. The planar transistor is built in layers and can have all of its connections in the same plane.

The first layer in a planar transistor is a base of semiconductor material. Many impurities are added to this base that allow it to be a better conductor. A second layer of semiconductor, with fewer impurities, is then put on top of the base. After the second layer is in place, the center of it is etched out, leaving thick edges of the second material around the sides and a thin layer above the base, in the shape of a square bowl.

A section of material of the opposite polarity than the initial two layers is then placed in the bowl. Once again, the center of this layer is etched away forming a smaller bowl. A material similar to the first layer of the planar transistor is then added. The second, third and fourth layers are all made flush with the top of the transistor.

The positive and negative components of the planar semiconductor are accessed on the same plane of the device. Metal connectors can be attached to the transistor after the components are in place, allowing the device to receive and emit electricity. The transistor receives input from the first layer and emits output from the fourth. The third layer is used to run a charge into the transistor so that it can amplify input.

Though the design of the device is a bit more complicated than earlier transistors, many planar transistors can be made at the same time. This decreases the amount of time and, subsequently, money needed to produce transistors and has helped paved the way for more affordable electronics. These types of transistors can also boost input to higher levels than earlier models of transistors.

In earlier transistors, the oxide layer that naturally forms on the suface of the semiconductor was removed from the transistor to prevent contamination. This meant that the delicate junctions between the positive and negative sections of the transistor had to be exposed. Constructing the transistor in layers, as Hoerni’s design called for, incorporated the oxide layer as a protective feature for the junctions.

EasyTechJunkie is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.
Discussion Comments
EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.

EasyTechJunkie, in your inbox

Our latest articles, guides, and more, delivered daily.