| 摘要 |
A lateral bipolar phototransistor having a floating, photosensitive base region is formed in a silicon layer on an insulator substrate. Insulated gate electrodes are formed above and below the base reigon and are voltage biased to create a field effect causing majority carriers to accumulate in the base region. The majority carriers accumulate in layers which face the respective gate electrodes and extend between an emitter and collector of the bipolar transistor. A bias voltage applied to the gate electrodes has a polarity opposite to a polarity of the majority carriers in the emitter and collector regions and is sufficiently high to bias field effect transistors constituted by the gate electrodes in combination with the emitter, base and collector of the bipolar phototransistor into cutoff. The accumulation creates a depleted base region with reduced parasitic capacitance and resistance, thereby enabling higher frequency operation and current gain.
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