A Page in the History of Transistors: Ingenuity in Post-War JapanApril 08, 2017 by Robin Mitchell
Learn about Japan's semiconductor journey to dominance in the global electronics industry.
Japan has been a dominant presence in electronics manufacturing for decades, but this wasn't always the case. Learn more about the history of Japanese electronics and how engineers helped Japan become a juggernaut in the electronics industry.
The West has developed many technological advances in electronics, but Japan has an incredibly rich electronics history. Japanese innovation spans from using a bucket of water to control crystal growth of germanium (more on that later) all the way to creating some of the world’s most iconic consumer products.
The device that gave birth to modern life: the point-contact transistor
The Invention that Changed the World
After the second world war, Japan's manufacturing sector was heavily damaged and had to be controlled carefully. The economy was in ruin and funding for technological projects was near impossible to get. When Bell Laboratories in America developed the point-contact transistor in 1947, the Japanese were desperate for the technology.
However, getting technical data was difficult. So Japanese scientists and engineers—armed with pens and notebooks—traveled to America to find out whatever they could. Sketches of the machinery were made, notes about the construction were jotted down, and every interaction they had with western scientists was documented.
The most famous account of this was Kazuo Iwama, who visited the US's transistor companies on behalf of the Tokyo Telecommunications Engineering Corporation which is now Sony Corporation. Iwama's notes and observations are now known collectively as the Iwama Report.
The first task for Japanese researchers was to experiment with germanium crystals to try and recreate the amplification phenomena. However, due to the youth of the technology and their limited resources, the researchers were not even sure how or why the devices exhibited the phenomena.
One method to replicate this amplification was developed by Makoto Kikuchi, one of the founding fathers of Japanese semiconductors. He used a pair of small needle-like wires to touch a piece of germanium.
Makoto Kikuchi, one of the driving forces in Japanese semiconductors. Image courtesy of the Semiconductor History Museum of Japan
However, no matter how much he tried, the device failed to amplify. This was because the germanium crystal was impure, which meant that the researchers had to find a way to create highly pure germanium crystals. The answer lied in a process called “zone refining”, which involves heating a slice of crystal and then moving it such that the impurities flow towards the heat while leaving pure crystal behind in the cooler region.
Developing Better Crystals
Of course, there was a major hurdle to overcome when it came to zone refining: the tech just did not exist in Japan. The funding needed to get the needed equipment was enormous—but this did not stop Japanese scientists. Putting their heads together and spending every waking hour, they began to develop their own machinery and ideas.
The American labs used highly precise equipment to draw a germanium crystal at a very slow speed, which is not possible by hand. Instead, the Japanese used a bamboo lever with a float in a leaky bucket which, over time, made the lever rise and draw the crystal out at just the right speed. The result of a leaky bucket and some ingenuity lead to the first point-contact transistors in Japan.
Another method for producing quality crystals was the Czochralski Process (1956). However, the needed equipment was also not available to the Japanese at the time which resulted in temperature control issues. For the crystal to grow correctly, the temperature had to be carefully controlled to within 0.1 degrees centigrade. For the Americans, this was relatively easy because they had the proper funding and equipment—but the Japanese had access to analog meters that could only measure in units of 1 degree.
To address this issue, light was reflected off the needle and projected onto a wall. Any slight variation in the needle would result in a more dramatic change in the projected light's position. That made it much easier to determine how the temperature was changing.
Crystal growth using the Czochralski Process (1956) using equipment not available to the Japanese at the time. Image originally published in Radio and Television News magazine.
The Birth of a Unique Transistor
A second transistor type (the first bipolar junction transistor) that became central in Japan's semiconductor industry was the grown-junction transistor. This transistor was made by adding impurities to molten semiconductor material during the drawing stage using the Czochralski Process.
However, grown-junction transistors had some major drawbacks involving the creation of the base region. Antimony was used to create the emitter/collector regions of the grown transistor as it is an N-type dopant. When antimony is used, it invades the P-type region, effectively destroying it.
One solution was to make the P region thicker but this resulted in transistors with poor characteristics. The Americans believed that the grown transistor would never be usable for devices such as transistor radios, but the Japanese were determined to make it work. The solution was to alloy tin with phosphorous when creating the P-doped region which resulted in a consistent base region that the antimony would not invade.
A grown-junction transistor. Image courtesy of David Forbes [CC BY-SA 3.0]
Due to the success of the manufacture, mass production of these grown-junction transistors began immediately. However, these devices completely failed and resulted in Japan's entire semiconductor production line halting which also stopped radio production. Luckily, Japanese researchers recognized that the problem was the tin phosphorous alloy. Instead of using tin, indium was alloyed with phosphorus and the result was a line of grown-junction transistors that worked fantastically in radio applications while having a yield of over 90%.
Sony's first transistor radio using Japanese transistors, the TR-55. Image courtesy of Sony.
Source: Birth of the Transistor: A video history of Japan's electronic industry
These are but a few innovative methods for producing electronics that the Japanese developed. It is this drive and ambition for electronics innovation that makes Japan arguably the world's capital for electronics.