MEASURING APPARATUS FOR DEEP LEVEL IN SEMICONDUCTOR

摘要

PURPOSE:To detect a deep level in a semiconductor even in case of much noise irrespective of large or small and slow or fast of variation of an optical current by connecting a capacitor with an external circuit and charging the optical current generated in the semiconductor in the capacitor. CONSTITUTION:When a light 2 is emitted to a sample 1', an optical current 4 flows to charge a capacitor 6. An operational amplifier 8 is disposed so that a potential 7 does not alter by the current 4 so that an output voltage 9 becomes equal to a voltage across the capacitor 6 charged by the optical current. Since an output voltage V0 is output by an integrated value of a designated time (t), a fine optical current can be collected as a large total amount. The current having a fast variation which can be hardly collected momentarily can be pre sumed for the momentary value of the current and its ageing change as a differ entiated value for a time in the reverse calculating from the variation of the output voltage V0. A signal having much noise can be obtained in high reliability according to a way of selecting an electrostatic capacity C and a sampling time.