Applied Physics

Fast and Efficient Photodetectors

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Science  24 Mar 2000:
Vol. 287, Issue 5461, pp. 2117
DOI: 10.1126/science.287.5461.2117e

Improved Internet access will depend on the development of technologies for moving signal rapidly. One approach is the “fiber to the home” proposal, which would utilize the speed and information capacity of optic fiber communication networks to replace the existing conventional wires that currently serve to connect homes to long-distance, optical communication trunks. This approach will require the refinement of elements of optical transceivers, including modulators and photodetectors, that ideally should be integrated with existing silicon technology.

Germanium-silicon (Ge-Si) heterojunction photodiodes are promising candidates for photodetectors because Ge film growth is compatible with Si processing and Ge has a band gap in the infrared, the wavelength regime used for optical communications. However, the lattice mismatch between Ge and Si results in defects and dislocations in the epitaxially grown Ge film that degrade the photodetector characteristics. Colace et al. introduce a simple technique to improve the Ge-Si photodetector response, a post-growth cyclic thermal annealing process that can reduce these defects. The observed photoresponse improves by a factor of 2 and exhibits a subnanosecond response time.—ISO

Appl. Phys. Lett.76, 1231 (2000).

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