| 摘要 |
PROBLEM TO BE SOLVED: To make detectable a short-circuit failure even for a sample to be measured having a very high resistance value by enabling a high-speed and high-sensitivity current measurement which has been difficult heretofore. SOLUTION: This tester is provided with a laser generating part 1, a laser scan part 2, a microscope 3, a current-voltage converter 13, and a front end amplifier 15 disposed between the sample 4 to be measured and the current- voltage converter 13. The front end amplifier 15 is provided with a resistor 5 connected in series between the sample 4 to be measured and the grounding potential, a constant voltage or constant current variable power supply 6, and a junction type FET in which a signal from the sample 4 to be measured is input to a gate, a source is connected to the grounding potential through a constant current source 11 and connected to the current-voltage converter 13 at the subsequent stage, and a drain is connected to a power supply 10. The operation bias of the junction type FET is performed by a bias circuit 9 connected to the gate and the constant current source 11 connected to the source.
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