The feasibility of using amorphous silicon photodetectors as receivers in optical interconnection is discussed. The amorphous silicon could be deposited on top of the silicon chip so that the entire chip area could be dedicated to processor and memory circuits. Utilizing the parallelism afforded by fabricating arrays of large numbers of modulators and receivers would provide communication bandwidth far in excess of electronic interconnects even though individual receivers operated at modest speed. A preliminary experiment was carried out to determine important issues such as photosensitivity and interfacing between the amorphous silicon sensor and crystalline silicon circuit. The results show that amorphous silicon photodetectors have high photosensitivity. A bipolar-junction-transistor voltage comparator or CMOS inverter can be used to amplify the photocurrent generated by the detector to the level required by very large scale integration circuits. Systems using amorphous silicon detectors could offer large-bandwidth parallel communication channels for multiprocessors, based entirely on proven, compatible materials and processes.
Stephen T. Kowel,
Charles A. Eldering,
"Amorphous silicon thin-film photodetectors for optical interconnection," Optical Engineering 34(3), (1 March 1995). http://dx.doi.org/10.1117/12.190450