JPH0154871B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor radiation detector capable of detecting fast neutron beams.

As shown in Fig. 1, the semiconductor radiation detector is
For example, phosphorus is diffused from a partial area of one surface of the P-type ultra-high resistivity silicon plate 1 to form an N region 2 to a predetermined depth, and a P ⁺ layer 3 is formed over the entire surface from the other surface. An electrode 4 made of, for example, aluminum is deposited on the surface of the N region 2, and an electrode 5 made of, for example, gold is deposited on the surface of the P ⁺ layer 3. When applying a reverse bias voltage to the PN junction between the remaining P region 11 and N region 2 of the silicon plate 1 via the electrodes 4 and 5, that is, a voltage with the electrode 4 side being positive, A depletion layer spreads within P region 11. When radiation is incident on this depletion layer, electron-hole pairs are generated, and a pulse current flows in which the holes are transported to the electrode 5 side and the electrons are transported to the electrode 4 side by the applied voltage. This pulse current is counted by a detector (not shown) to measure the intensity of the incident radiation. However, since neutron beams have no charge, they do not have any effect on the orbital electrons or the Coulomb field of the atomic nucleus other than nuclear reactions.
Therefore, no electron-hole pairs are generated. Therefore, in the case of detecting fast neutron beams, a plastic plate containing hydrogen atoms, such as a polyethylene plate 6, is used as a silicon plate 1.
It was worn on top of the . When the fast neutron beam 7 is incident, the protons 8 ejected by elastic collisions enter the depletion layer and generate electron-hole pairs, so that they can be detected in the same way as other radiations.

In this way, the present invention is a semiconductor that does not require a substance that causes an (n/p) reaction, that is, a substance that causes protons to be knocked out by elastic collisions between fast neutrons and hydrogen atoms, to be mounted on the front surface for fast neutron beam detection. The purpose is to provide a radiation detector.

This objective is achieved by implanting hydrogen ions into the surface of the semiconductor substrate of the detector or into the electrodes provided on that surface.

Embodiments of the present invention will be described below with reference to the drawings. In each figure, including FIG. 1, common parts are given the same reference numerals. In Figure 2,
As shown in Figure 1, N
Region 2 is formed, and hydrogen ions are implanted into this region B by an ion implantation method. This ion implantation is performed, for example, at an acceleration voltage of 100 keV and a dose of 1×10 ¹⁵ cm ^-2 or more. When a fast neutron beam 7 is incident with a reverse voltage applied to the PN junction between both electrodes 4 and 5 of this detector, protons 8 are knocked out by elastic collisions, and electron-hole pairs are created within the depletion layer. Since a pulse current flows between the electrodes 4 and 5, the incidence of a fast neutron beam can be detected. In FIG. 3, hydrogen atoms have been implanted into the P ⁺ layer 3. In this case, the incident fast neutron beam 7
After passing through the depletion layer in the P region 11, the protons act on the hydrogen atoms in the P ⁺ layer 3 to generate protons 8, so that fast neutron beams can be detected in the same way as in the case of FIG. In FIG. 4, hydrogen atoms are injected into the electrode 4. In FIG. Therefore, the fast neutron beam 7 is connected to the electrode 4
Protons 8 are generated by acting on the hydrogen atoms within.

Since the structure of the radiation detector according to the present invention is similar to that of conventional detectors, it can naturally be used as a detector for other radiations. In the case of γ-rays, secondary electron beams due to the photoelectric effect and Compton effect are detected, so the output shows a continuous spectrum with respect to the pulse height as shown by curve 41 in Figure 5. Therefore, the fast neutron beam shown by curve 42 is The cases can be clearly distinguished.

The present invention is applicable not only to a detector using a PN junction as described above, but also to a detector in which, for example, aluminum is vapor-deposited on the surface of a high resistivity semiconductor plate to form a surface barrier, and a reverse bias is applied to this surface barrier. It can also be applied to a detector that forms a depletion layer. In that case, hydrogen atoms are implanted into a resistive layer for ohmic contact as in the example shown in FIG. 3, or into an electrode as in the example shown in FIG. Furthermore, the present invention can be applied even when the conductivity type of each region of the semiconductor board of the previous embodiments is reversed.

As explained above, the semiconductor radiation detector according to the present invention is capable of detecting fast neutrons by itself by injecting hydrogen atoms into the low resistance region or electrode of the semiconductor plate, and is furthermore capable of detecting fast neutrons than the conventional semiconductor radiation detector. It can also be used to detect other types of radiation in the same way as the above detector, so it can be used extremely effectively.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of detecting a fast neutron beam using a conventional semiconductor radiation detector, Fig. 2 is a sectional view showing an embodiment of the present invention, and Figs. 3 and 4 are different from each other. FIG. 5, which is a sectional view showing an embodiment, is a model diagram of the output pulse height of the detector according to the present invention. 1...P type silicon plate, 2...N area, 3...
P ⁺ layer, 4...electrode.

Claims (1)

[Claims] 1. A semiconductor radiation detector characterized in that hydrogen ions are implanted into the surface of a semiconductor substrate or an electrode provided on the surface.