JPH03124071A - Semiconductor radiation-detecting element - Google Patents

Abstract

PURPOSE:To prevent a drop in a collection efficiency of carriers by forming a metal layer whose work function with reference to a vacuum is smaller than a work function with reference to a vacuum of p-type and n-type amorphous silicon and whose thickness does not obstruct a transmission factor of a radiation. CONSTITUTION:Metal layers 5 whose work function with reference to a vacuum is smaller than a work function p-type and n-type amorphous silicon with reference to a vacuum and whose thickness does not obstruct transmission of a radiation are formed between individual pin diodes 2. By this constitution, the metal layers 5 come into ohmic contact with p-type and n-type amorphous silicon layers. Thereby, a barrier or the like such as an electric field or the like is not formed between the p-type and n-type amorphous silicon layers. Consequently, when a radiation is incident, carriers are generated in an i-layer. Since the barrier or the like such as the electric field or the like is not formed, the carriers are sent to a measuring circuit 4 with good efficiency as an electric current through individual collection electrodes 3. As a result, a radiation dose is measured by means of the measuring circuit 4.

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention relates to a semiconductor radiation detection element.

(Prior art) Detection targets of semiconductor radiation detection elements include the dose rate of air radiation in facilities that use radioactive isotopes and radiation generating devices, and the surfaces and There is radiation contamination of the surface of the human body.

By the way, FIG. 2 shows a tandem type detection element, and this tandem type detection element is applied to a solar cell, and the detection target has a weak transmittance of visible light. Its structure is that a pi film made of amorphous silicon is placed on a substrate 1.
In addition to laminating a plurality of n diodes 2, these pIn
Collection electrodes 3 are arranged above and below the diode 2, respectively, and these collection electrodes 3 are connected to a measurement circuit 4. When there is incident light in such a configuration, carriers are generated in the i-layer and a current flows. This current is sent through each collecting electrode 3 to a measuring circuit 4.

However, in the above configuration, since the pin diode 2 is directly stacked, the adjacent n-type amorphous silicon
type amorphous silicon, which causes each p
Due to the interaction between the in diodes 2, the collection efficiency of carriers generated by the incident light is reduced. By the way, such a tandem type detection element is applied to radiation detection, but even if it is applied to radiation detection, there is no bonding between adjacent n-type amorphous silicon and n-type amorphous silicon as described above. occurs, resulting in a decrease in carrier collection efficiency.

Therefore, it is difficult to apply it to measuring the dose rate of air radiation in facilities that use radioactive isotopes, or to measuring radiation contamination on the surfaces of items that exit from the radiation-controlled area of the facility.

(Problems to be Solved by the Invention) As described above, a junction occurs between adjacent p-type pressed crystalline silicon and n-type amorphous silicon, reducing carrier collection efficiency.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a semiconductor radiation detection element that improves carrier collection efficiency without forming a bond between adjacent p-type pressed crystalline silicon and n-type amorphous silicon.

[Structure of the Invention] (Means for Solving the Three Problems) The present invention stacks PIN diodes and has a structure in which the work functions with respect to vacuum are the same as those of p-type and n-type amorphous silicon, respectively, between the layers of these PIN diodes. This semiconductor radiation detection element attempts to achieve the above object by forming a metal layer smaller than the function and having a thickness that does not impede the transmission of radiation.

(Function) By providing such a means, there is ohmic contact between the p-type and n-type amorphous silicon and the metal layer, and no electric field barrier is formed and the carrier collection efficiency does not decrease. .

(Embodiment) An embodiment of the present invention will be described below with reference to the configuration diagram shown in FIG. Note that the same parts as in FIG. 2 are given the same reference numerals.

Between each p1n diode 2 is a molybdenum Mo
A metal layer 5 is formed. The molybdenum Mo forming this metal layer 5 has a vacuum work function smaller than that of p-type and n-type amorphous silicon, and the thickness of this metal layer 5 prevents the transmission of radiation. It is formed to a certain degree. The measurement circuit 4 also has a function of applying a reverse bias voltage to each pin diode 2 through each collection electrode 3, and detecting the current generated in each pin diode 2 due to the movement of carriers to determine the radiation dose. have.

With such a configuration, molybdenum MO is p-type and n-type.
Each makes ohmic contact with the type amorphous silicon layer. As a result, an electric field barrier or the like is not formed between the p-type and n-type amorphous silicon layers.

Therefore, when radiation is incident, carriers are generated in the i-layer, and since no electric field barrier is formed as described above, these carriers are efficiently sent to the measurement circuit 4 as a current through each collecting electrode 3. As a result, the measurement circuit 4 measures the radiation dose.

In this way, in the above-mentioned embodiment, between each pl rhodiode 2, the work functions for vacuum are p-type and n-type.
Since the metal layer 5 of molybdenum Mo is formed to have a thickness smaller than the vacuum work function of the amorphous silicon and to a thickness that does not impede the transmission of radiation, it is possible to
No junction is formed with the type amorphous silicon, and the carrier collection efficiency does not decrease. This increases the S/N during radiation measurement.

Note that the present invention is not limited to the above-mentioned embodiment, and may be modified without departing from the spirit thereof. For example, the metal layer 5 is not limited to molybdenum MO, but is made of a material whose work function with respect to vacuum is smaller than that of p-type and n-type amorphous silicon, and which is formed to a thickness that does not impede transmission of radiation. It's good to have.

[Effects of the Invention] As detailed above, according to the present invention, there is no bonding between adjacent p-type extruded crystalline silicon and n-type amorphous silicon, and the semiconductor radiation detection can improve carrier collection efficiency. We can provide elements.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of a semiconductor radiation detection element according to the present invention, and FIG. 2 is a block diagram of a conventional element. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Pin diode, 3... Collection electrode, 4... Measurement circuit, 5... Metal layer.

Claims (1)

[Claims] PIN diodes are stacked, and a metal layer is formed between these PIN diodes, the work function of which is smaller than the vacuum work function of p-type and n-type amorphous silicon, and which has a thickness that does not impede the transmission of radiation. A semiconductor radiation detection element characterized by: