26) Measuring Instrument Converted from a Photo Enlarger
Photo: A measuring instrument made by Hitachi Ltd., to measure lifetime of
Ge single crystals
There were neither materials nor measuring instruments available
for semiconductor development in Japan, when it was started literally from
scratch. Even after signing a contract with Western Electric Company to obtain
the technological know-hows, Japanese companies could receive only three volume
text of "Transistor Technology." They, therefore, had to develop
all the necessary equipment by referring to the simple figures and photos
in those books.
In those days I had heard Tetsuo Tsukamoto, who was a key person of the transistor
development group at Sony, mutter "I wish I could see the backside of
this instrument shown on the photo by turning it over." I could not laugh
at it.
Likewise, they had to develop testing equipment and measuring instruments
by themselves, too. The photo shows a measuring instrument made by Hitachi
to measure lifetime of Ge single crystals which employed so called light injection
method. They first set up a fixed needle electrode on a bulk crystal and applied
a reversed bias to it. Then, they measured the amount of minority carrier
current into the needle electrode, while changing the relative position of
focused light in slit-shape against the needle.
Takashi Tokuyama, a chief researcher of Central Research Laboratory of Hitachi
at the time said, "Since no commercial equipment was available, we utilized
an upper light source by remodeling that of a photo enlarger. The lifetime
of the first crystal we grew was 7 micro second." (By courtesy of Tokuyama)