Superior materials used to make countless types of devices
Unlike silicon semiconductors in integrated circuits, compound semiconductors are made of two or more elements. These semiconductors are found in many instruments we use in daily life, for example, laser diodes and photodetectors for optical fiber communication systems; various transistors for wireless communication systems such as cell phones; light sources for CD, DVD and Blu-ray players; and white LEDs.
Adjusting the composition ratios of the elementary materials makes it possible to create compound semiconductor materials with desirable physical properties on semiconductor substrates.
Furthermore, applying multiple compound semiconductor films onto the substrate in a three-dimensional manner according to device design parameters allows the development of devices with an infinite range of possibilities in terms of functions and characteristics. This is the main reason why compound semiconductors are so attractive. These chips can lead to the conception of technologies unimaginable with mere silicon chips, including electronic instruments such as high-frequency transistors and next generation power devices as well as photonic devices such as semiconductor lasers.
The world’s largest general producer of compound semiconductors
About half a century ago in 1961, Sumitomo Electric became the first company in the world to recognize the potential in developing and marketing compound semiconductor substrates. Since then, we have advanced into research of not only substrates but product applications as well. For example, we recently succeeded in developing and commercializing a gallium nitride substrate for use in violet laser diodes for Blu-ray drives. Throughout the years, we have grown to become the largest general producer of compound semiconductor substrates in the world.
I have been involved in the research, development and commercialization of compound semiconductor devices for over thirty years since I joined Sumitomo Electric. For the past ten years, I have working on R&D of next-generation power devices incorporating silicon carbide and gallium nitride semiconductors that have wide energy bandgaps.
An extremely difficult process in the production of compound semiconductors is uniformly crystallizing thin films only several nanometers thick on entire crystal substrates. In the 1980s when we first began development, there were no competent crystal growth equipment on the market, so we had to begin with building our own device. After much painstaking work, we finally completed our own crystallization device and used it to crystallize thin films with multiple layers, which we then employed in the production of a semiconductor laser. This laser boasted the best performance in the world at the time, and I was overjoyed when we unveiled it at an academic conference in the United States.
Incredible materials that realize an engineer’s dreams
Our research division has a culture of nurturing the ideas of each individual member. When an idea proposed to senior staff has been approved, we begin studies on small-scale models and then move on to larger scales following periodical evaluations. In this encouraging environment, we confronted the challenge of making a compound semiconductor device.
Coming up with a great idea, translating that idea into an innovatively designed device employing compound semiconductors made by combining different types of elements and then successfully transitioning into industrial production: I believe this process epitomizes the dream of engineers everywhere. Since this process is, however, very tough, I am even now struggling for success.
I give talks and lectures whenever I can in order to generate interest in compound semiconductors within the general public as much as possible. I believe this is one of my responsibilities as a fellow of Sumitomo Electric. This March, I visited the U.S. Patent and Trademark Office and gave a talk to 200 patent examiners about the fascinating properties of compound semiconductor devices, what the future holds for this technology and our company’s activities in promoting this field.
Energy conservation for a clean future
So how can this technology change the future? One answer is through energy conservation. About five percent of all the energy consumed globally is lost through inefficient power devices used to convert or control power. To minimize the energy loss, vigorous efforts have recently been made for the R&D of power devices using semiconductors with wider energy bandgaps. In the near future, a certain proportion of power devices using silicon semiconductors will be replaced with those using compound semiconductors. This trend will contribute to the conservation of energy in society.
In the field of optics, progress is being made in the development of semiconductor lasers, photodetectors and other devices with wavelengths unheard of until now. For example, devices employing the infrared region of the optical spectrum characterized by long wavelengths are expected to be applied in the areas of medical instruments, food inspection, security and wireless communications. Devices employing the green region with a little longer wavelengths may be applicable to semiconductor lasers that cannot be realized conventionally. Application of the green region will enable the invention of projectors small enough to be fitted into a cell phone. In terms of shorter wavelengths, the use of UV light sources will also become a reality. These compact light sources will be able to replace the hazardous mercury lamps currently in use. In this manner, we anticipate the adoption of various types of compound semiconductors will lead to a cleaner, energy-efficient and more comfortable world.
I believe it’s not an exaggeration to say that farther down the road, compound semiconductor devices may one day be used to efficiently store energy or even generate power. When our firm first began developing compound semiconductors, we couldn’t imagine what the world would be like fifty year into the future. In the same manner, I believe this technology will help us achieve several decades later what we could only dream of now.
Of course, these past thirty years of R&D have not all been smooth sailing. In truth, our failures outnumbered our triumphs. However, the birth of new successful products was possible only because we refused to fear failure and were committed to learning from our mistakes.
My message to young researchers
It is my hope that young researchers will take a long-term view of the future, measuring time in terms of decades, and then set a target every year for the ultimate goal of realizing your long-term dreams, so that you will gain fulfillment in your daily work and build on your accomplishments.