Commemorative lecture at the 38th Honda PrizeAward Ceremony on the 16th November 2017

Research and Development of SiC andPractical Use

Dr. Hiroyuki Matsunami
Professor Emeritus, Kyoto University

Dr. Hiroyuki Matsunami
Professor Emeritus, Kyoto University■Date of BirthJune 5th, 1939

■Biography
1962: Department of Electronic Engineering,
Faculty of Engineering, Kyoto University
1964: Master’s Degree, Graduate Schoolof Engineering, Kyoto University
1964: Research Associate, Kyoto University
1970: Doctor of Engineering, Kyoto University
1971: Assistant Professor, Kyoto University
1976–1977: Visiting Associate Professor,
North Carolina State University, U.S.A.
1983: Professor, Kyoto University
2003: Mandatory retirement from Kyoto University
and appointed as Professor Emeritus
2004–2012: Director, Innovation Plaza Kyoto,
Japan Science and Technology Agency■Academic Society/Association Activities
President, SiC Alliance, General Incorporated
Association (2015–)
The Japan Society of Applied Physics; The Institute ofElectronics, Information Science and Communication
Engineers; The Institute of Electrical Engineers ofJapan; The Japanese Association for Crystal Growth;IEEE (The Institute of Electrical and Electronics
Engineers, Inc.)■Selected Publications
Silicon Carbide Vol. I, II (Akademie Verlag, 1997)
Silicon Carbide—Recent Major Advances— (Springer, 2003)
Semiconductor SiC Technology and Applications (Nikkan
Kogyo Shimbunsha, 2003)
Semiconductor SiC Technology and Applications Second
Edition (Nikkan Kogyo Shimbunsha, 2011)
Wide Gap Semiconductors—From Dawn to the
Frontlines—(Baifukan, 2013)■Awards and Honors
2001: The 1st Yamazaki-Teiichi Prize (in the field ofsemiconductors and semiconductor devices),Foundation for Promotion of Material Scienceand Technology of Japan
2002: The Commendation for Science and Technology by
the Minister of Education, Culture, Sports, Scienceand Technology in 2002 (Research Contribution Award)
2004: The 4th (2003) Research Achievement Award, The
Japan Society of Applied Physics
2004: The 41st (2003) Research Achievement Award,
The Institute of Electronics, Information Science
and Communication Engineers
2005: The SSDM Award-2005
2013: The 2012 Asahi Prize (pioneering research of power
semiconductor silicon carbides)
2016: The IEEE David Sarnoff Award
2017: The Academia PrizeAlso, appointed to Fellow of the Japan Society of Applied
Physics, Fellow of the Institute of Electronics, Information andCommunication Engineers, and Life Fellow of the IEEE

This report is the gist of the commemorative lecture at the 38th Honda Prize Award Ceremony at the Imperial Hotel, Tokyo on
16th November 2017.

It’s a great pleasure and honor for me to receive the Honda Prize. I would like to take thisopportunity to express my deepest appreciation to the nominator for recommending me andto the members of the Selection Committee for choosing me.
Last year, I was awarded the IEEE David Sarnoff Award, and, recently, major advances havebeen made around silicon carbide (SiC) on a global scale, and now I am here to receive the
Honda Prize. To be blessed with a series of unexpected good fortunes and happy events, I
myself have become overwhelmed and at a loss about how to express my feelings.
Today, I would like to deliver a talk entitled “The Path a Crazy Boy Walked” as acommemorative lecture. It was when I was still a fledgling young man that I started to workon an outrageous research subject, and at first, I could not even see where I was heading.
Still, I never forgot my former mentor’s word. He often said: “An engineering technology
becomes meaningful only when it is used in society,” which has always been my motto to live
up to. Also, I have never changed my attitude of “not imitating others” and “having courage tochallenge something that others haven’t done” even until now.
The contents of the talk are shown here. First, I would like to talk about ICT innovation
through the development of semiconductors. Let me explain the current situation. I heardthat most of the people present here are not experts in science & technology. If you arefamiliar with that field, you may find this talk tedious. Therefore, I would like to humbly ask
you to remain patient to the end.

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Next comes the effective use of electric energy. In this part, I will explain about the importantrole that power semiconductors play. And, also, from the viewpoint of energy conservation, I
want to emphasize why now is the time that we should give our full attention to siliconcarbide (SiC). I conducted basic research at Kyoto University, which became my turning point
and led me to make an epoch-making presentation. I would speak about the basic research I
conducted at university, in which I studied crystal growth by “step-controlled epitaxy,” andthe devices. I proposed such as an SBD (Schottky-barrier diode) and a MOSFET(metal-oxide-semiconductor field-effect transistor) using this method.
For a research outcome to be actually used in society, it has to be put into practical use bybusiness enterprises; however, they only make such efforts when that is promoted by anational project with a guideline showing “which direction to go.” I would like to explain how
we have addressed this challenge, and at the end of this, I would like to talk about future
prospects.

Fig. 1〈Fig. 1〉 Since my profile has already been introduced, let me omit it here.
When I was young, I heard from my former mentor that the Club of Rome gave a warning in
1968, saying: “If the current trend continues, human beings will continue on toward
destruction. Something must be done to deal with global warming, food shortages andpopulation growth.” In order to solve these complex problems, the Honda Foundation wasestablished in 1977 by Soichiro Honda and his younger brother Benjiro. And in the field ofecotechnology, under the banner of four items, namely, sustainability, paradigm shift,
innovation, and life frontier, they instituted Japan’s first international prize. I would like toexpress my heartfelt admiration to their keen insight.

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■ ICT Innovation through the development of Semiconductors (20th century)

Fig. 2〈 Fig. 2 〉 Now, I would like to briefly explain how much we presently benefit fromsemiconductors.
I think many of you have seen this picture before; this is the world-first computer, which
included vacuum tubes. It seems to have worked a little from 1946 to 1955. It was asuper-jumbo computer using vacuum tubes measuring 30 m in depth, 2.4 m in height and 90
cm in width, and it could be used only at night. Due to its enormous power consumption, it
had to be used only in the nighttime; otherwise, a blackout would take place in the area
where it was situated.
If one of the 17,000 vacuum tubes got broken, it took 30 minutes to repair it, and even if
reliable tubes were used, one tube got broken every two days. That was the way it was then.
It was the invention of a transistor using semiconductors that brought about the computers
evolution to modern models.

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Fig. 3〈Fig. 3〉 Actually, my younger brother asked me “What is a semiconductor?” the other day,so I think it would be better to briefly explain about it. In order to pass an electric current,
you need a conductor. But, a bare wire is dangerous and you cannot touch it, so you need touse insulators like rubber, to cover it. A semiconductor falls between a conductor and an
insulator, whose properties are literally something between them.
However, semiconductors have hidden interesting properties. In terms of materials, silicon in
the periodic table plays a major role. And, also, the III-V group and the II-VI group on bothsides of silicon in the table are also used as semiconductors.

Semiconductors form acrystalline structure called a diamond structure, which has the same structure as that ofnatural diamonds.

Fig. 4〈Fig. 4〉 Use of semiconductors enables conversion between various types of signals andenergy. Presently, semiconductor devices that enable conversion between electricity andelectricity and between electricity and light are widely used throughout the world.

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Fig. 5
〈Fig. 5〉 The invention of transistors led to the development of an integrated circuit, andthen, a program was added to it; thus, a microcomputer was realized around 1970. After that,the use of cutting-edge CMOS (complementary metal-oxide-semiconductor) further advanced
the development of computers, and their development has continued until today. This is thegreat contribution that semiconductors have made, and at the same time, the invention oftransistors has promoted the progress of electronics, which has led to major changes in society.

Fig. 6〈Fig. 6〉 Along with the shift in computers from desktop PCs to tablet PCs, semiconductors
have been increasingly used for digital cameras, the most recent iPods, iPads andsmartphones, etc. In such an area, however, a motor to turn a hard disk that has been used in
a computer is not needed anymore. Instead, they all come loaded with semiconductors. A
large amount of memory is stored in the cloud, and you take only things you need out of it.
That is the way things work now.

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Fig. 7
〈Fig. 7〉 Another remarkable contribution of semiconductors to society is associated with
the interconversion of light and electricity. The invention of light-emitting diodes (LEDs) led
to the development of laser diodes, which is used in a laser pointer. Solar cells are playing a
principal role in renewable energy. After the introduction of blue LEDs, white LED lamps,
the combination of blue LEDs and yellow fluorescence agents, were produced. Probably, in a
few years, almost all the fluorescent lamps will be replaced by LED lights. Thus, we can saythat during the 70 years after the invention of transistors, semiconductors emerged and havecome to play a leading role in society and totally changed our view of the world.
■ Effective Use of Electric Energy (Role of Power Semiconductor)
Well, so far, I have talked about the role of electricity in information processing orcommunication, where a relatively small amount of electric energy is used. In an area wherelarger amounts of electric power are used, such as when you need to drive a motor to move anelectric car, power semiconductors come to play an important role.

Fig. 8〈Fig. 8〉 Since electric energy is very easy to use, its consumption has continued to rise. In

6order to make up for power shortages, power plants have to be built; however, since the greatearthquake in 2011, most nuclear power plants have ceased to operate, and fossil fuels suchas coal, petroleum, and LNG (liquefied natural gas) are being burned at thermal power plants.
That means we are producing a lot of CO2 and accelerating global warming, which is not goodfor the environment. If we can reduce the energy loss resulting from power consumption, it
will become possible to launch a new industry, which will also satisfy your requirements.
It is power semiconductors that are utilized in the use of electric energy. Semiconductors bear
the responsibility of reducing the energy loss taking place there. Or I would rather say that
we are expected to focus our efforts on this important point. Silicon has so far played a majorrole in power semiconductors, however, silicon carbide has rapidly come to the forefront.

Fig. 9〈Fig. 9〉 A SiC semiconductor is made from silicon carbide, which is a compound created by
combining silicon and carbon in a proportion of one to one. Raw materials for silicon are all
around us here on earth. For example, you can take silicon from sand. If you burn something,charcoal is produced. Since silicon carbide consists of such things, we certainly havesufficient raw materials.

7Fig. 10
〈Fig. 10〉 As you all know, direct current is sent from batteries. Direct current flows in one
direction and returns to the ground through a grounding wire. On the other hand, alternating
current flows while changing its waveform over time as shown in the figure. Both current andvoltage demonstrate a similar change. Personal computers and smart phones are powered bydirect-current batteries. But power plants provide alternating-current power. Therefore, as
you can see, conversion between direct current and alternating current is very important.

Fig. 11〈Fig. 11〉 For converting power from alternating current to direct current, you need diodes
that have a property of allowing electricity to flow only in one direction, while blocking it in
the opposite direction. From electric power companies, alternating-power with 50 Hz isprovided in East Japan, and alternating-power with 60 Hz is provided in West Japan.
Household appliances you are using at home such as inverter air conditioners, inverter
refrigerators, inverter washing machines, or inverter fluorescent lamps are designed toconvert power from alternating current to direct current, and then, to cut it off with fastswitching to create a high-frequency alternating current. For these appliances to achieve that,8they have to have transistors. There are two types of transistors, but today, we want to pay
attention to MOSFETs. We need diodes and transistors to achieve conversion between direct
current and alternating current.
By the way, when you try to rotate an AC induction motor in the alternating-current state,
first, the alternating current is converted to direct current, which is then cut off with fastswitching of an inverter to rotate the motor. This is the operating principle of high-speed
rotation.
■ Economic Use of Energy and Expectation for SiC Power Semiconductors
Then, what impact does the use of silicon carbide (SiC) have on the effective use of electricity?

Fig. 12〈Fig. 12〉 The figure shows the flow of electricity from power plants to users. During theelectricity transmission process, frequency conversion, conversion from direct current toalternating current, and conversion from alternating current to direct current take place, andthis process is believed to result in the loss of about 5% of all the electricity generated.
Let’s say one user has a 2 kW air conditioner. About 10% of that power is wasted as heat.
Since currently used bipolar-type inverters called Si-IGBTs (silicon-insulated gate bipolartransistors) have a problem of allowing electricity to flow in a reverse direction due to slow
switching speed, this causes a significant energy loss. That means the electric power thatreaches users is 85% of the entire power generated at power plants. This is a serious problem.
Replacing silicon IGBTs with silicon carbide MOSFETs at places where conversion is
performed can greatly reduce energy loss.
9Fig. 13
〈Fig. 13〉 This figure shows what silicon power devices are like and what they are used for.
As you can see, if silicon carbide MOSFETs are created, considering their performance,
silicon IGBTs, which are currently the mainstream of power devices, can be almost
completely replaced by them.
Silicon MOSFETs are used at low power levels, which is the limitation determined by theproperty of the material. Silicon carbide could be used at power levels tens of times higher
than that at which silicon MOSFETs are used. This is a significant difference.

Fig. 14〈Fig. 14〉 This is a figure that compares the physical properties of silicon and silicon carbide.
When a comparison is made by using general-purpose inverters, you can see that the limit ofthis physical property makes a profound difference in performance.
Since the energy gap of silicon carbide is about three times as much as that of silicon, it canbe used at a temperature more than three times as high as the temperature where silicon canbe used. Also, in addition to being more highly efficient, silicon carbide is more resistant to10

voltage and makes it possible to draw out large quantities of electric power. As it is small insize, it does not need a large cooling device. According to circumstances, it does not needwater; just wind will do. Silicon Carbide is expected to demonstrate remarkable highperformance.
■ Fundamental Research (Contribution of Kyoto University)—Turning Point, Epoch-Making—At first, I did not realize that silicon carbide would be a useful material for making powerdevices. My policy to do something that other people have not done led me to silicon carbide,and since then, I have conducted a study on it. After finally finding that it can be used for
power semiconductors, I have come to realize the great difference between silicon IGBTs andsilicon carbide MOSFETs.

Fig. 15〈Fig. 15〉 This figure shows the history of research on silicon carbide. Shockley and his
fellow researchers were the first to succeed in producing germanium transistors. Those days,
however, when placed under the temperatures of 60°C or over, the difference between p-type
and n-type became indistinguishable, as a result of which transistors did not operate. Thatgave rise to a growing expectation for electronics that can operate at higher temperatures.
In order to promote research for development of devices that can be used at high temperatures,country-level projects were launched in America and other countries such as the Netherlands,
the United Kingdom, and Japan. Since silicon had not appeared yet at that time, when Lely, aGerman researcher, made an announcement that it became possible to produce high quality
crystals of silicon carbide, everyone jumped at that. Thus, the first round toward thedevelopment of silicon carbide started with great anticipation in the mid 1950’s. However,silicon came on stage, and it was found to be usable under temperatures of up to 125°C. That
led to a decline in the interest in silicon carbide, because it was difficult to grow its crystals.

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Since crystals of silicon carbide in those days were very thin and had irregular shapes, device
makers were not motivated to produce devices with such a thing. Around 1968, while I was
writing my master’s thesis and doctoral thesis, I was conducting research on how electrons
move in semiconductors, which means I tried to delve into details of the physical properties ofsemiconductors from the angle of what is referred to as transport phenomenon. In afrustrating situation, I was wondering what fruit my engineering research would produce,
and when it could make a contribution to society.
At that time, research on silicon was becoming mainstream, so business enterprises weremaking efforts not be left behind in that research race. In addition, Gunn diodes, gallium
arsenide-based semiconductors, were introduced to the world. When direct current voltage issimply applied, gallium arsenide gives off microwaves. A lot of university researchers got
involved in research on gallium arsenide. However, I knew that just going in the same
direction in the same phase would end up just holding a subordinate position, and also I
thought that without the right equipment, I would not be able to do anything. In my master’s
thesis and doctoral thesis, I discussed that II-V semiconductor compounds have a composition
that is difficult to crystallize, and that even if that was successfully done, it was unlikely to
be used in the world.
On the other hand, however, silicon carbide came to be known to have excellent physicalproperties in the first round. In particular, since silicon carbide was found to be able to be
used at high temperatures and have high resistance to radiation, I thought this material
might make it possible to do something that could not be realized with silicon. Also, it was
already known those days that it was possible to create blue light emitting diodes, which
many people were waiting for, if p-type and n-type were able to be controlled by siliconcarbide. We could not make an electronic device because there was no substrate. Then, I will
make silicon carbide on silicon and make a transistor in that manner. That was a dream I had.
The interatomic spacing of silicon differs from that of silicon carbide by as much as 20%. I
applied for research funding, but I was not selected. When I look back, it was really crazy ofme to challenge such a thing. I simply wanted to try something that seemed impossible andthat no one else had ever tried. And my target was to produce electronics that could be usedat high temperatures or transistors that have high resistance to radiation and could still be
used. I launched my research with a focus on blue light emitting diodes and silicon carbide
transistors on silicon. Now I look back and think that it was because I was working on these
two things that I came to find an excellent crystal growth method called a “step-controlled
epitaxy” method. If I had been pursuing only one thing, instead, I imagine it would havetaken a much longer time before silicon carbide could come under the spotlight as a material
for power devices around the world.

12Fig. 16
〈Fig. 16〉 We worked on the creation of blue LEDs. If you melt silicon in a crucible ofgraphite and put a seed crystals in it, p-type and n-type layers are formed on the crystal.
SANYO Electric Co., Ltd. put this technology to practical use and produced marketableproducts. When this was achieved, I enjoyed a sense of fulfillment, and I said to myself: “Ah, I
finally see the fruits of my research.”

Fig. 17〈Fig. 17〉 Now, let me move on to the subject of the epitaxial growth of silicon carbide on
silicon. The photo shows a hand-built equipment. Since it was very easy for my researchgroup to create such a thing in the university, I immediately worked on my experiment. In an
attempt to apply silicon carbide on a silicon plate, I added source gases while keeping thesilicon at a high temperature, which led to an increase in the activation level of the siliconsurface. As a result, since silicon carbide grew rapidly after it adhered to silicon, which took
place in quick succession, I did not succeed in producing single crystals. It took about 10
years to produce single crystals of silicon carbide with high reproducibility.

13After I found adding source gases onto the active surface of silicon substrate did not work
well, I came up with the idea of covering the surface with something like a cushion andadding gases onto it. I applied this idea and added carbon-based gas onto a silicon substrate
at a low temperature, which solved this problem. I had different students try this experiment,
which produced the same result. Thus, I succeeded in realizing its reproducibility.

Fig. 18〈Fig. 18〉 After this, which I call my “10 years of endurance,” I announced the realization ofsilicon carbide MOSFETs on silicon with delight and excitement. I think it was the first suchannouncement relating to such a discovery in the world. I expected that the transistor
characteristic would demonstrate a saturated curve, however, a leak was detected somewhere.
Actually, due to irregularity caused by the 20% difference in interatomic spacing between
silicon and silicon carbide, the interface of the p-n junction of the silicon carbide did not
become flat, but developed a jagged structure, which resulted in the concentration of large
electric field and the flow of leakage current. I realized that after all, I had to produce crystals
on silicon carbide substrates. However, such substrates were not commercially available.

14Fig. 19
〈Fig. 19〉 As a last resort, I decided to use a crystal like the one in the figure. It is used as anabrasive or as a material for fire-proof bricks. After putting sand called quartz sand and cokein a tremendously large-scale furnace, you add salt and sawdust so that gas can escape, andthen raise the temperature. This is a chunk of what was made in such a furnace.
Those days, when I went to a company producing these, a person working there told me:“Surface parts are useful because they are easy to pulverize, but chunks of crystals are hardto pulverize, so if you collect and put them in a cardboard box, I will send them to you later.”Accepting his kind offer, I took out small crystals on the surface of which single crystals are
exposed with my students using a chisel and a hammer. Since a chunk has a shape like the one
shown in the figure, you have to polish its back parallel to a single crystal face. Since it is thehardest material next to diamonds and boron carbide, sometimes it is very difficult to polish its
back perfectly parallel to the front face. You can produce crystals by raising the temperature of
the obtained wafer and adding the gases necessary for the growth of silicon carbide.

Fig. 20〈Fig. 20〉 One day, I received a report, saying: “I have always seen a strange mosaic pattern,15

but I cannot see that today.” One student seemed to have made a conscious effort to growsilicon carbide on a polished surface out of a spirit of adventure. I saw it and found thatstudent succeeded in making a uniform and beautiful surface.

Fig. 21〈Fig. 21〉 I checked this by simple evaluation methods. When it was applied with etching byusing slightly high-temperature alkali, a totally different result was obtained. Etch pits on
one crystal were close to hexagons. The others were like triangles, placed on both sides of aboundary ditch on a surface. The triangles on one side had the 180-degree inverted shape of
those on the other side. Later, when I observed them by using the reflection energy electron
diffraction method, it was found that the former was a zigzag stack of hexagonal crystals
which was the same as a substrate, and on the other hand, the latter was the growth of cubic
crystals of silicon carbide. That was really a good job. This happened in 1986.

Fig. 22〈Fig. 22〉 Experts in crystal growth probably know that when a substrate has a step
structure, making crystal growth start from the step edge will lead to the proper growth of16

the entire crystal, but since we are mainly working on device research, we did not have thisidea at first. If we had advanced our research based on the logic that effectively using steps
will promote high-quality crystal growth, other people might have said; “He is amazing,” butactually, in our case, it was by accident that we successfully used that structure. I believethat was a blessing for me.

Fig. 23〈Fig. 23〉 Immediately, I started to make a p-n junction. With silicon carbide on silicon, there
was a leak at 2 V and over in the reverse direction; however, when I made a p-n junction with agrowth of 2 µm, withstand voltage rapidly went up to 100 V. I knew what I should do after that.
I examined all the optimum conditions regarding in what direction and to what angle theinclination should be provided.

Fig. 24〈Fig. 24〉 Based on the findings, I introduced Schottky barrier diodes in 1993, and in 1995,
I succeeded in raising withstand voltage to 1.75 kV at a stroke with a full-fledged Schottky
barrier diode structure.

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A thickness of 13 µm and a specific on-state resistance of 5mΩcm² were realized. This had atremendous impact on the power device industry. Because if the same thing is done by using silicon,
you can achieve up to only 200 V. To hear that, many people handling power devices started tocome to us. After our announcement, we were vigorously pursued by various organizations.

Fig. 25〈Fig. 25〉 In the late 1990s, MOSFETs were produced, and by using them vertically as shownin the figure, we finally were able to throw off the limitations of silicon. However, the crystal
face they were using was the least desirable one. I thought that they would be replaced bytrench MOSs.

Fig. 26〈Fig. 26〉 After examining a planer structure and characteristics of a MOSFET on theconventional face (0001) and on a vertical face (11-20), it was found that it would be possible
to improve performance up to 20 times as high as previously seen at one time.
I said: “the age of trench MOSFETs will arrive soon,” a very advanced company in Kyoto called18

“ROHM” introduced what I did at Kyoto University in industry-academia collaboration in an
appealing manner, and, as I will describe later, developed the world’s first trench MOSFETs.
■ Present Technologies of SiC Power Devices

Fig. 27〈Fig. 27〉 Wafers, for the development of which experts have spent a lot of time and energy,
have generally had a size of 100 mm in diameter, but recently, ones with a size of 150 mm (6inches) have been becoming more mainstream. They have already demonstrated ones with asize of 200 mm in diameter. When you compare them with the stone-like chunks I used before,
you can see how much improvement has been made. In response to our success in operating
devices, material makers have invested great efforts to improve materials thus far.

Fig. 28〈Fig. 28〉 In 2001, a German company called Infineon showed how much loss can be reduced by
the use of silicon carbide Schottky diodes. After considering business-related factors, the company
started to produce them right away. Silicon cannot achieve a withstand voltage of around 1000 V.

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In the figure, a silicon carbide Schottky diode and a silicon p-n diode are compared, whichshows that the use of the latter caused a significant loss. By this comparison, the superiorityof silicon carbide Schottky diodes was demonstrated.

Fig. 29〈Fig. 29〉 After that announcement, a lot of attention was attracted instantly; however,since it was after the burst of the economic bubble in Japan that this announcement was
made, this technology was not commercialized immediately. Nine years after that, in April
2010, ROHM announced the mass production of SiC Schottky barrier diodes.

Fig. 30

Fig. 31〈Fig. 30 and 31〉 In December of 2010, ROHM announced the mass production of planar
MOSFETs which are capable of operating at temperatures of up to 200℃. Then, they
announced high-performance of trench MOSFETs at an academic conference. Furthermore,in 2015, ROHM created modules equipped with trench MOSFETs basting current of 180 A,
which was really an amazing result. This was a truly remarkable event in Japan as well as
the first time in the world that this was achieved.

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■ Development of National Project toward Practical Applications
So far, I have explained to what extent technologies have been developed. Now, I want to talkabout the reality that we cannot advance our research without companies’ support and efforts.

Fig. 32〈Fig. 32〉 I listed many things in the figure, but the point I want you to give attention to is
the Lehman Shock that took place in 2008. The industrial world found itself in a criticalsituation. In such a situation, the government found it was necessary to take some actions torevitalize businesses, and as part of such efforts, the “Funding Program for World-leading
Innovative R&D on Science and Technology” called FIRST, and the “New Material Power
Semiconductor” project were launched. In such an environment, I made various proposals
and participated in various projects.

Fig. 33〈Fig. 33〉 At the same time, the SiC Alliance came into being. As I mentioned earlier, whenthree different programs are proceeded with at the same time separately, all the people
participating in the programs look at only their sponsors. They are doing the similar things

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without ever associating with each other, which is not reasonable. So, to provide a table
where they can share what they have, the alliance was organized. The organization has been
incorporated, and presently, it is operating as a general incorporated association.
In the SiC Alliance, we consider in which direction to go in the future from a neutral
standpoint and make various proposals. Also, we discuss what needs to be done in the next
program, how we can effectively report the fruits of research through science communication
as well as how we can support the industry-academia-government collaboration.

Fig. 34〈Fig. 34〉 Mitsubishi Electric Corporation was the first to work on the commercialization of
our research achievement. At first, Mitsubishi produced an air conditioner, which is capableof reducing switching loss by 60%, like the one in the figure by using silicon carbide Schottky
diodes and silicon IGBTs. According to this year’s announcement, their new air conditioner isequipped with an artificial intelligence, having a function of automatically turning off theswitch when there is no person around it. It also has a function of sensing the movements of aperson and adjusting the direction of cool or warm wind accordingly. It adopts “Active Switch
Compressor,” which facilitates switching.
It is also reported that its energy saving effect is greater in winter than in summer. In
summer, you need to lower the room temperature from 35 or 36°C to 28°C, at most; however,in winter, you need to raise the room temperature from single-digit cold to as high as 18°C,
which requires a considerable amount of power.

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Fig. 35
〈Fig. 35〉 First, they were used in hybrid-type subway vehicles. In an experiment with theuse of silicon IGBTs and silicon carbide Schottky diodes, about 40% of loss reduction wasachieved. When a train is running at high speed, a regenerative brake can be used, and then,the regenerated energy is sent to another train running nearby, which is how the system
works. An Odakyu train fully equipped with silicon carbides also achieved about 40% of loss
reduction.

Fig. 36〈Fig. 36〉 Currently, silicon carbides are used in various trains in different regions. This is a
train running on the Yamanote Line. Old-type brown-colored trains used to run on the Kanjo
Line in Osaka. Silicon carbides were introduced to trains which are currently running.

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Fig. 37
〈Fig. 37〉 Elevators. Since they stand side-by-side, by sending regenerated energy to eachother, 65% of loss reduction can be achieved.

Fig. 38〈Fig. 38〉 They are also used in automobiles, hybrid vehicles. At first, in a test run, theysucceeded in improving fuel economy by 5%. I heard it is amazing to make a 5% improvement
at once simply by changing devices. It has been announced that they will be released around
2020.

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Fig. 39
〈Fig. 39〉 Honda Motor Company began to use silicon carbide power devices for fuel cellvehicles in 2016. Now, they are already being commercially supplied to various companies
including taxi companies.
Yesterday, I went to the Smart Hydrogen Station in Odaiba to learn various things such as how
to fill a cylinder. It is truly an energy-saving product. It uses a solar cell to produce hydrogen byelectrolysis of water. Indeed, it is totally an economical and energy-saving vehicle.
Besides, the fuel cell-powered car I tried was a five-seat sedan, whereas today four-seat fuelcell cars dominate the world. This increase in capacity stems from its driving section which ispacked under the hood; this was enabled by the overall compactness of parts designed to
manage that structure. I really enjoyed its comfortable ride.

Fig. 40〈Fig. 40〉 They are controllers for solar cells of which I have already explained.

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Fig. 41
〈Fig. 41〉 The most exciting use of silicon carbide will be found in JR Tokai. It wasannounced that it would be put into practical use in 2020. That means both new siliconcarbide-powered automobiles and trains will appear during the year of the Olympic games
here in Japan. In addition, I find the strategy to be taken is very amazing. JR Tokai is using
N700 series Shinkansen train-cars, but since a long time has passed since they wereintroduced, they will have to be replaced. At the timing of their replacement, JR Tokai isgoing to start to use silicon carbides, and specifically, perform an overall review oftransformers, converters, inverters, and motors, which will enable an 11 ton weight reduction
per 16 train cars. Next year, JR Tokai is planning to install those silicon carbide devices inthe trains on a four cars-by-four cars basis. Presently, 16-car trains are running between
Tokyo and Osaka, but 12-car trains and 8 car-trains are also running in western Japan. If
standard products are prepared on a four cars-by-four cars basis, it will become possible topromptly meet orders in the future, instead of offering designing systems from scratch
responding to individual orders. This Shinkansen system initiated mainly by JR Tokai ismuch appreciated by other countries in the world, but even when this system is employed by
one of those countries, they don’t need to change its design from region to region. If standard
products become available, it will become possible to provide quick delivery at a low price.
That is what is going to happen.

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Fig. 42
〈Fig. 42〉 After all, how to control a motor determines how much energy can be saved.
Controlling general-purpose motors used in the industrial world and daily life would produce
the highest energy-saving effect. This means its CO2 equivalent would be reduced as well.
However, there are various types of motors, so it is difficult to clearly say with what specificinverter and how motors should be controlled.

Fig. 43〈Fig. 43〉 It is the Super Cluster Program in the Kyoto area that now I’m looking at withgreat anticipation.
The Ministry of Education, Culture, Sports, Science and Technology (MEXT) supported local
regions for 11 years through the cluster project, which however, did not lead to substantial
results. Accordingly, the MEXT decided to stop the project. With that, it was decided that JST
would take responsibility for proceeding with the project.

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I proposed that incentives should also be provided for businesses. Since silicon carbide powerdevices run at extremely high speed, ringing oscillations occur. Thinking that we needexperts in electric circuits to prevent that phenomenon, we asked professionals at the
Department of Electrical Engineering at Kyoto University to join us. It seems like we are going
to produce very interesting results. More than 10 companies have produced successful results.

Fig. 44〈Fig. 44〉 Here is one successful example by one of the small and mid-sized enterprises. This
company developed a very interesting idea called HEMS (Home Energy Management
System). First, install a 10 kW photovoltaic battery, or solar cell, at home, and then, bring a
Nissan Leaf to connect to the battery. This way, electric energy can be transferred.

Fig. 45〈Fig. 45〉 According to the data presented here, replacing silicon IGBTs, which have been
widely used, with silicon carbide MOSFET will be able to achieve a 42% loss reduction.

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Presently, a quick charging device has been placed in the underground parking lot of “Miyako
Messe” owned by Kyoto City. If you pay a parking fee, you can freely use it to charge your car.
After that, with a general constructor, I have made collaborative efforts in the development of
BEMS (Building Energy Management System), in which one big enterprise that showedinterest in this system participated, which also led to the development of CEMS (Community
Energy Management System) in Maui, Hawaii. At the current moment, the president of thatcompany went to Canada and is likely to receive support from the Canadian government.

Fig. 46〈Fig. 46〉 Small and mid-sized enterprises are making use of this system and growing steadily.
I think this is an amazing thing about Kyoto. A variety of new problems arise spirally, and they
are solved, which leads to the acquisition of new users. This is how things are working.

Fig. 47

Fig. 48〈Fig. 47 and 48〉 Another company I would like to introduce is Fukushima SiC Applied
Engineering Inc., which is exclusively working on the practical application of silicon carbide.
Their products can be made only with silicon carbide, not with silicon. As part of the attempt
to prepare for the replacement of klystrons, they provide composition examples ofacceleration neutron generators.

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Presently, a very large piece of equipment called a cyclotron is generally used as anaccelerator, but if you use silicon carbide, it will not be necessary to use that. One of theadvanced variations resulting from the use of silicon carbide is a BNCT (Boron Neutron
Capture Therapy) cancer treatment apparatus, which can be used for the treatment of large
internal organs such as the liver, the gallbladder and the pancreas. If you disperse thetherapeutic drug with boron by using DDS (Drug Delivery System), you can cure cancer, even if thecancer cells are scattered. Although this sounds like a dream, it could be a treatment in the future.
■ Summary and Future Prospects

Fig. 49〈Fig. 49〉 Now, let us consider our future direction. It is needless to say that now siliconcarbide power devices are widely used around the world, but I still emphasize the importanceof mastering devices.

Fig. 50〈Fig. 50〉 In Japan, the technology-push approach is well supported; however, unless Japan30

becomes like America and Europe, where the attitude of “If you make something good, I will
be happy to use it” is prevalent, those who deserve the reward will miss it. Unless we address
this issue now, it will become a serious problem for the industrial world. Now is the time tomake a shift from “technology push” to “market pull.” Also, it is necessary to cultivate young
researchers and help them to get familiar with a specific way of handling such a product. I
want to emphasize that it is very important.

Fig. 51〈Fig. 51〉 Thanks to its national projects, Japan is presently two to three years ahead ofAmerica.
In the U.S., President Obama announced “Power America” in the State of the Union addressin 2014, and a new project launched in February 2015 has been working. The goal was toestablish a foundry to produce reasonable power devices and encourage small and mid-sizedenterprises to work on the development of power electronics with 7 billion yen provided fromthe government and another 7 billion yen from a newly established regional consortium.
Expecting to see their efforts bearing fruit in about two years, people in CPES (Center forPower Electronics Systems) who are experts in applying new technologies are eagerly waiting.
CPES, established at the Virginia Polytechnic Institute and State University, commonly
known as Virginia Tech, has a large group of researchers with more than 15 years ofexperience. I have received a lot of reports on electric circuits showing what great results theyattained by using silicon carbide. Japan belatedly started to follow them.

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Fig. 52
〈Fig. 52〉 At the International Conference of Silicon Carbide and Related Material held in
September 2017, the participants from all over the world emphasized “Moving from Niche to
Mainstream.” To see such a global trend around silicon carbide, the committee decided tolaunch the conference with this catch phrase.

Fig. 53〈Fig. 53〉 Since I heard many officials from related ministries and agencies supporting us
are here today, I would like to make a proposal. Judging from what the super cluster in Kyoto
experienced, when industry-academia collaboration is working quite well, big enterprises arelikely to join, which can unexpectedly lead to open innovation. I would like you to make surethat this flow will continue to work smoothly. Recently, every ministry or agency has come toemphasize the importance of industry-academia collaboration and open innovation. For a
research group that was hastily arranged in response to such an announcement, it is usually
impossible to produce an outcome in three years to five years, unless the group members haveprevious achievements. I often hear people say even a probability of success of one hundredthor even three thousandth will do; however, since budgets for research projects are limited, I
hope they are to be used as effectively as possible.

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The primary problem facing young researchers is that since they cannot receive financial
support for their research unless they join a project, they move from one project to another.
Today’s environment surrounding academic research is totally different from that of the day
when I was a crazy boy doing whatever I wanted. Researchers who want to conduct researchout of curiosity or out of the spirit of seeking truth cannot receive financial support.
It has been 13 years since the transformation of national universities into independentadministrative institutions was carried out. As a result, management expenses grants have been
reduced by 1% a year. Due to the impact of budget cuts on universities, three large universities
have already been closed. Additionally, there is no system that encourages young researchers to
do what they really want. I want you to give careful consideration to this. I believetransformative research that has a potential of producing great outcomes is very important.

Fig. 54〈Fig. 54〉 This is my future dream. I want silicon carbide power devices to be used formaglev linear motor cars.

Fig. 55〈Fig. 55〉 At the same time, it is possible to extend their application to large vessels or aircraft.
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Fig. 56
〈Fig. 56〉 They are my favorite quotes of the pioneers. Edison said: “Genius is one percent
inspiration and ninety-nine percent perspiration,” which means that a great result a genius
produces is not only the product of inspiration but the product of ninety-nine percent
perspiration.
Shockley, the creator of transistors, used the expression “Creative failure,” which sounds veryclear when translated into Japanese. “Accident favors prepared mind,” which means that if
you always use your mind, when there is an accident, you will come up with a creative
solution. It is very important to have such a mind-set.
He also said: “Try the simplest case or approach the simplest case,” which means that when
you achieve something after making a lot of efforts, you should stop and think how you can dothe same thing in a simpler way. That is my favorite quote.

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Fig. 57
〈Fig. 57〉 At the end, I would like to express my sincere appreciation for all your support.
Especially, I have had great help from Professor Kimoto at Kyoto University, who is now
playing a major role in the world arena. Dr. Nakamura, who was with ROHM and now works
at Osaka University, was the first to introduce the results produced at Kyoto University to
the industrial world, and also, made a great contribution to the realization of mass
production of SBDs and DMOSs, and realized the practical application of trench MOSFET
ahead of others. I would like to extend my heartfelt gratitude to my students who worked
very hard in various areas, the company that produced blue light emitting diodes, Mr. Kuroda
who also made a great contribution when we first developed MOSFETs by using thestep-controlled epitaxy method, and the late Akira Itoh who greatly contributed to thedevelopment of Schottky diodes. And I cannot forget Dr. Yano who made a contribution to thedevelopment of MOSFETs. Additionally, I would like to express my deepest appreciation to
many people at the academic society and various support organizations. At the very end, I
want to say thank you to my family, especially my wife, Fumiko, from the heart for letting me
pursue what I wanted to do. Please excuse me for talking too long. Thank you very much.

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