| 摘要 |
PURPOSE:To facilitate the expansion of a depletion layer and thereby to increase the detection output level of a photosensor, by using as the photosensor a P-N junction of low impurity concentration which is formed by a layer with implanted ions of low impurity concentration, which is provided on the surface of a semiconductor substrate, and by an epitaxial layer. CONSTITUTION:A photosensor is formed of a P-N junction which is formed by a layer 5 with implanted ions and an epitaxial layer 2. The impurity concentration of the layer 5 with implanted ions is set to be 10<11-13>cm<-2>, substantially the same with that of the epitaxial layer 2. Since the impurity concentration of the epitaxial layer 2 is also low due to its structure, a junction approximate to a P-I-N structure having low impurity concentration can be obtained. This photosensor is employed with a resistor 9 for detection and a DC power source 10 connected between a cathode contact region 8 and a substrate 1, and it forms an equivalent circuit shown in the figure. When infrared rays are applied to the photosensor, a generation combination current is generated therein, causing a fall of voltage in the resistor 9. This fall of voltage is amplified by an amplifier 11, so as to obtain an output signal.
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