Self-aligned SiGe-base heterojunction bipolar transistor byselective epitaxy emitter window (SEEW) technology |
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Authors: | Burghartz JN Comfort JH Patton GL Meyerson BS Sun JY-C Stork JMC Mader SR Stanis CL Scilla GJ Ginsberg BJ |
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Affiliation: | IBM Thomas J. Watson Res. Center, Yorktown Heights, NY; |
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Abstract: | In the device a SiGe epitaxial base is integrated in a structure which uses in situ doped epitaxial lateral overgrowth for the formation of the emitter window and the extrinsic base contact. Nearly ideal I -V characteristics have been achieved for a base width of 60 nm with an intrinsic base resistance of 4.6 kΩ/□ and for emitter widths down to 0.4 μm. A DC collector current enhancement factor of 3.1 was obtained relative to a Si homojunction transistor with a 1.25 times higher intrinsic base resistance. The breakdown voltage BVCBO is identical for both Si and SiGe devices, even though the collector-base depletion region is partly overlapped with the reduced-bandgap SiGe strained layer. The lower BVCEO, measured for the SiGe-base transistor, is due to the higher current gain. Based on these results the fabrication of high-speed bipolar circuits that take advantage of SiGe-base bandgap engineering seems possible using selective epitaxy emitter window (SEEW) technology |
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