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Title: Al/n/sup +/Ge/n/sup +/Si heterojunction ohmic contacts

Thesis/Dissertation ·
OSTI ID:6721234

The resistance associated with conventional ohmic contacts to Si is too large to be successfully used for future submicron Si VLSI devices; thus, other schemes for forming ohmic contacts to Si must be explored. A theoretical and experimental study was conducted to determine if flow resistance ohmic contacts to Si could be formed using a heterojunction structure consisting of a thin layer of a narrow bandgap semiconductor between the contacting metal and the Si. The total contact resistivity, r/sub c/, of an n-type heterojunction contact was estimated from a model that treated the heterojunction as two back-to-back Schottky energy barriers whose magnitudes were calculated from boundary conditions on the electric displacement and charge at the interface. By assuming that current transport across the metal semiconductor and heterojunction Schottky barriers occurred by thermionic field emission or field emission, the contact resistivity of each barrier was calculated and the sum of the three values was taken as r/sub c/ of the heterojunction contact. To measure r/sub c/, AL/n/sup +/Ge/n/sup +/Si contacts are made to TLM devices and Kelvin four terminal devices; Al/n/sup +/Si contacts were fabricated concurrently for direct comparison of r/sub c/ values.

Research Organization:
Minnesota Univ., Minneapolis (USA)
OSTI ID:
6721234
Resource Relation:
Other Information: Thesis (Ph. D.)
Country of Publication:
United States
Language:
English