JPS6161708B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor radiation detector that can be used without bias and provides high sensitivity.

A conventional general semiconductor radiation detector is shown in FIG. 1 is, for example, an n-type Si substrate, 2 is an Au electrode, 3 is an Al electrode, and 4 is an I/V converter. In normal radiation measurement, a bias voltage is applied so that the Al electrode 3 is positive and the Au electrode 2 is negative. This is to expand the depletion layer generated on the Au electrode 2 side by applying a bias voltage, thereby increasing the sensitivity to radiation. Although radiation detection is theoretically possible in the non-biased state with the structure shown in Figure 1, the depletion layer based on the contact potential difference can only be made thinner on the Au electrode 2 side, so R ₁ in Figure 1 indicates Although it is sensitive to radiation incident near the Au electrode 2,
There is a problem in that there is only a slight sensitivity to radiation incident near the Al electrode 3, which is indicated by R ₂ . For the same reason, it is impossible to compare the intensities of the radiation fluxes R ₁ and R ₂ .

An object of the present invention is to provide a semiconductor radiation detector that can provide high sensitivity even when used in an unbiased state and has excellent positional resolution of radiation intensity.

That is, in this invention, a second metal electrode that does not form a depletion layer and a first metal electrode that does not form a depletion layer is provided on one side of the semiconductor substrate, and a depletion layer is also formed on the other side. A fourth metal electrode that does not form a depletion layer with the third metal electrode is provided. This improves the sensitivity to radiation and further improves the positional resolution of the radiation intensity.

A detector structure according to an embodiment of the present invention is shown in FIG.
In the figure, 11 is an n-type Si substrate with Au on its surface.
An electrode (first metal electrode) 12 and an Al electrode (second metal electrode) 13 are provided insulated from each other, and an Au electrode (third metal electrode) is also provided on the back side.
14 and an Al electrode (fourth metal electrode) 15 are provided. Figure 3 shows the Au electrode 12 of this detector,
14 in common to the I/V converter 16,
The Al electrodes 13 and 15 are grounded, so that both the radiation fluxes R ₁ and R ₂ can be efficiently detected by the depletion layer formed on the Au electrodes 12 and 14 side.

In FIG. 4, the front and back Au electrodes 12 and 14 are separately connected to I/V converters 16 ₁ and 16 ₂ , respectively. In this way, the radiation flux
It is possible to compare the intensities of R ₁ and R ₂ , improving the positional resolution.

As described above, according to the present invention, when semiconductor materials of the same volume are used, the sensitivity to radiation is improved and the positional resolution of radiation intensity is improved compared to the conventional one.

FIG. 5 shows the Au electrodes 12 and 14 each divided into a plurality of pieces. With this structure, it is possible to detect the incident position of radiation fluxes such as R ₃ and R ₄ in the figure, and to perform energy analysis on radiation fluxes such as R ₁ and R ₂ . I can do it. As shown in FIG. 6, not only the Au electrode but also the Al electrode may be divided into a plurality of pieces, and the same effect as shown in FIG. 5 can be expected with this as well.

In order to improve the electrical insulation between the electrodes, the gap may be filled with an insulating resin 17 (for example, polyurethane resin or epoxy resin) as shown in FIG. 7a, or grooves 18 may be provided as shown in FIG. 7b. It is also effective to set Furthermore, the arrangement of the Au electrodes 12, 14 and the Al electrodes 13, 15 may be modified as shown in FIG. 8 with respect to the configuration shown in FIG.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a conventional radiation detector;
FIG. 2 is a diagram showing the structure of a radiation detector according to an embodiment of the present invention, FIG. 3 is a diagram showing an example of the configuration of a detection circuit using this detector, and FIG. 4 is a diagram showing the configuration of another detection circuit. 5 and 6 are diagrams showing the structure of a radiation detector of another embodiment in which the electrodes are divided. FIG. 7 is a diagram showing a modification of the separation structure between the electrodes. FIG. 8 is a diagram showing an example. FIG. 6 is a diagram showing a modification of the electrode arrangement. 11...n-type Si substrate, 12...Au electrode (first
metal electrode), 13... Al electrode (second metal electrode), 14... Au electrode (third metal electrode), 15
...Al electrode (fourth metal electrode), 16...I/V
Converter, 17... Insulating resin, 18... Groove.

Claims (1)

[Claims] 1. A first metal electrode that forms a depletion layer on one of opposing surfaces of a semiconductor substrate and a second metal electrode that does not form a depletion layer are provided in a mutually insulated state, and a depletion layer is formed on the other side. A semiconductor radiation detector characterized in that a third metal electrode that produces a depletion layer and a fourth metal electrode that does not produce a depletion layer are provided in a mutually insulated state. 2 Using n-type Si as the semiconductor substrate, the first and third
The semiconductor radiation detector according to claim 1, wherein Au is used as the metal electrode, and Al is used as the second and fourth metal electrodes. 3. The semiconductor radiation detector according to claim 1, wherein each of the first and third metal electrodes is divided into a plurality of parts and faces each other.