AVALANCHE MULTIPLICATION AS A GAIN MECHANISM IN PHOTODIODES.
STANFORD UNIV CA STANFORD ELECTRONICS LABS
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The feasibility of a fast, high-gain photodetector based on the phenomenon of avalanche multiplication in semiconductors has been investigated. Such a detector would be a definite requirement for communication systems using light as a carrier, as well as for possible optoelectronic data processing systems. It has previously been reported that in the demodulation of microwave-modulated light an improvement in the signal-to-noise ratio can be achieved by operating conventional photodiodes under the conditions of avalanche multiplication. In the present study different amplification possibilities offered by avalanche multiplication are evaluated theoretically on the basis of the physical properties of available materials. Straightforward multiplication of photogenerated carriers in the highfield region of a semiconductor junction is recognized as the most promising mechanism. Based on the process of carrier multiplication in a high electric field, criteria for the design of an optimized avalanche photodiode and for the choice of the best semiconductor material are developed. The results of the study indicate that it is possible to achieve a silicon photomultiplier with a quantum efficiency-bandwidth product of the order of 100 GHz for the detection of light up to a wavelength of over 9000 Angstroms.
- Electrooptical and Optoelectronic Devices