Photosensitive pulse oscillator

A new type of semiconductor photosensitive device has been developed, differing from photodetectors used hitherto in the characteristics and the operation mechanism of the device. In the present device, stable oscillation is observed in the (n⁺-p⁺- n-n⁺)-p⁺structure of silicon in the applied voltage range, two ～ several hundred volts, with illumination above a threshold light intensity. The oscillation frequency increases linearly with the light intensity. For instance, with variation of light intensity 0.1 mW, the frequency changes by 3.6 kHz for the applied voltage of 30 V. With increasing applied voltage, the threshold light intensity and the oscillation frequency decrease. The frequency is expressed byA(L - 0.05)V_{a}^{-0.64}which agrees well with the experimental results. With rising temperature, the frequency varies little though the threshold light intensity decreases. The large output peak power of oscillation (12.5 W at 100 V) is obtained. In this paper, the fundamental characteristics and the operation mechanism of the device are presented.