TNAG-1508-FCO40-2066-Guangdong-nuclear-power-station-project-at-Daya-Bay-safety-c-1987 — Page 87

A

componenets, and to simulate space condition (such as solar wind on the surface of the moon) for purposes of space exploration. very extensive field of application of ion beam technology still

remains to be explored and utilized.

Neutron Radiation Doping of Monocrystal Silicon

the

of

Silicon must undergo doping when used in the manufacture semi-conductors. Five-valence phospherous must be incorporated in pure monocrystal silicon in order to produce an n-type semi- quality conductor. A major problem or great difficulty for the and finished product rate of semi-conductors is ensuring evenness Diffusion or smelting of phospherous doping and accurate dosage.

methods may be used, but the best results are achieved by

using

neutron transmutation doping.

Neutron

transmutation

doping

involves

silicon in an atomic reactor and

placing

bombarding

the

it

monocrystalline

with neutrons. A nuclear reaction occurs when the nuclei of the silicon atoms are hit by neutrons. The silicon is transmuted into phospherous. The penetrative force of the neutrons is

extremely

high, and the interior

and exterior

of the

monocrystalline

silicon

receive

almost equal

bombardment.

Therefore, doped

phospherous produced by this method is much more even than

that

produced by the diffusion method.

Also,

since the amount of

neutron radiation is precisely controllable,

so is the dosage of

doped phospherous.

The

are products

fairly

consistent.

The

neutron bombardment efficiency is high as is the utilisation rate

of the original monocrystalline

silicon. By using neutron

transmutation phospherous doping,

silicon controlled rectifiers

can be produced. The finished product rate can

be more than

3