| 摘要 |
PURPOSE:To obtain the characteristic of an photoelectric transducing operation correctly, by utilizing the fact that a photocurrent depends on an applied voltage, and solving a specified expression by numerical computation. CONSTITUTION:For example, a plurality of lower electrodes 2 are formed with Cr on a glass substrate 1. An i-a-Si layer 3 covers the electrodes. A p-a-Si layer 4 forms a barrier together with the layer 3. An ITO is used for an upper electrode 5. A photodiode is formed by the layers 3 and 4 and the electrodes 2 and 5. In an equivalent circuit of a reading device using said diode, the expression of relation I is obtained. In this expression, Va is a voltage, which is applied to the photodiode; V0 is an output voltage; Cd is the capacitance of the diodes: Cs is the synthesized capacitance of wiring capacitance and the input capacitance of an amplifier; and Iph is a photocurrent, which flows from the diode when light is projected. The following expression is obtained from the expression I. The expression is solved by computation, and the characteristic of the photoelectric transducing operation, which agrees with the actually measured value, can be obtained. Namely, the expression is V0={1/(Cd+Cs)} {Iph(V1)DELTAt+Iph(V2)DELTAt...+Iph(Vn)DELTAt}, where n.DELTAt=Ts (accumulated time) and Iph(Vn) is the value of the photocurrent at the applied voltage Vn.
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