JPH0738452B2 - Self-integrating photoconductive infrared sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a shape in the vicinity of an output reading area of an infrared sensor so that excess minority carriers generated in a crystal by infrared rays are not captured by an interface state on a side wall of the crystal. A self-integrating optical infrared sensor with improved

[Prior Art] In a conventional self-integrating photoconductive infrared sensor, as shown in FIGS. 2 and 3, a positive electrode 1 for applying a bias electric field, a negative electrode 2 and an output readout electrode 3 are provided on a crystal surface. Carriers generated in the crystal due to infrared rays are integrated by moving the drift region 4 from the electrode 1 to the electrode 2. The integrated carrier was detected as a potential difference in the output readout area 5 (A. Blackburn et al., Infrared Physics, Vol. 22 (1982) page 57; T. Ashley (T. Infrared Physics, Vol. 24 (1984), 25 pages.

[Problems to be Solved by the Invention]

However, in the conventional sensor, as shown in FIG. 2 and FIG. 3, since the contour line is bent at the boundary between the drift region 4 and the output read region 5, the bent portion 7 has The carrier flow is not smooth, that is, the carriers are easily captured by the interface states of the crystal-type wall near the same place, so that there is a problem that some of the integrated carriers are recombined and the output decreases. ..

An object of the present invention is to provide a self-integrating photoconductive infrared sensor in which the shape of the read region is improved so that excess minority carriers do not recombine with the interface states on the crystal sidewall near the output read region.

[Means for Solving the Problems]

The self-integrating photoconductive infrared sensor of the present invention comprises two electrodes arranged to face each other on the crystal surface, a read electrode near one of the electrodes, and a crystal region between the two electrodes. A contour line extending from the one electrode to the other electrode has a shape of a smooth continuous curve, and lines of electric force in the vicinity of the side wall of the crystal region are parallel to the contour line.

[Action]

The operation of the self-integrating infrared sensor of the present invention will be described with reference to FIG. In the figure, the same components as those of the conventional example are designated by the same reference numerals as those in FIG. 2 and FIG.

The self-integrating infrared sensor of the present invention comprises a plus electrode 1, a minus electrode 2, an output read electrode 3, a drift region 4 and a read region 5 for applying a bias electric field. In addition, 6 shows a line of electric force corresponding to the flow of carriers.

Excess minority carriers generated in the crystal of the drift region 4 due to infrared radiation drift and are integrated by the electric field applied between the electrodes 1 and 2. The integrated carriers reach the output read area 5 and are output as a potential difference. When the electric flux line 6 corresponding to the flow of carriers sharply bends in the vicinity of the location 7 as shown in FIGS. 2 and 3, the carriers recrystallize with the interface states on the crystal side walls, and the output decreases. In order to avoid this output reduction, the drift region 4 to the read region 5
It is necessary that the electric lines of force 6 are smoothly connected. That is, as shown in FIG. 1, by adopting the shapes of both regions without singular points, it is possible to prevent the output from decreasing.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

The self-integrating infrared sensor used in the examples is a photoconductive type in which a positive electrode 1, a negative electrode 2 and an output reading electrode 3 are attached to a HgCdTe crystal 10 having a band gap of 0.1 eV by gold vapor deposition. The flow L of the drift region 4 is 600 μm,
The length 1 of the read area 5 is 42.6 μm. Further, in the sensor of the present invention, the contours of the drift region 4 and the output read region are The HgCdTe crystal 10 is processed into a shape represented by. Here, x is a distance measured in the negative electrode direction with the center of the positive electrode as the origin. In this example, Wa = 63 μm,
l ₁ = 21.35 μm was used. That is, the width of the positive electrode is 63
The width of the negative electrode is 17 μm.

63 μm drift area for a conventional sensor, ie FIG. 2, on the same chip with the sensor of the present invention,
The minus electrode width was 38.5 μm, the drift region width was 63 μm, and the minus electrode width was 17 μm for the sensor shown in FIG. The drift area length of all three sensors is 600 μm, and the read area length is 42.6 μm. The thickness of the sensor, that is, the crystal thickness is 8 μm.

As a result of measuring the output voltage by irradiating three sensors including the present invention with 500K blackbody radiation, if the output of the conventional sensor of FIG. 2 is normalized to 1, the output of the conventional sensor of FIG. The value of 1.2 and the output of the sensor of the present invention was 1.5. As described above, it was found that the sensor of the present invention exhibits a high optical response of 1.25 times or more as compared with the conventional type cesar.

〔The invention's effect〕

As described above, according to the present invention, the self-integration type is designed by designing the contour of the sensor in the vicinity of the read electrode portion so that the excess minority carriers are not captured by the interface states of the crystal sidewalls near the read electrode portion. The optical response of the photoconductive infrared sensor can be improved.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a self-integrating photoconductive infrared sensor of the present invention, and FIGS. 2 and 3 are plan views showing a conventional self-integrating optical infrared sensor. 1 ... Plus electrode, 2 ... Minus electrode, 3 ... Read-out electrode, 4 ... Drift region, 5 ... Output read-out region, 6
…… Electric lines of force, 7 …… Bending part.

Claims (1)

[Claims] 1. A crystal surface is provided with two electrodes arranged to face each other, a read electrode is provided in the vicinity of one of the electrodes, and a crystal region between the two electrodes is provided from the one electrode to the other electrode. A self-integrating optical infrared sensor, characterized in that the contour line facing to is shaped like a smooth continuous curve, and the lines of electric force near the side wall of the crystal region are parallel to the contour line.