Tunneling at the Emitter Periphery in Silicon-Germanium HBTs

Sean P. McALISTER  Craig STOREY  Stephen J. KOVACIC  Hugues LAFONTAINE  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E84-C    No.10    pp.1431-1436
Publication Date: 2001/10/01
Online ISSN: 
DOI: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Joint Special Issue on Heterostructure Microelectronics with TWHM 2000 (Topical Workshop on Heterostructure Microelectronics 2000))
Category: SiGe HBTs & FETs
Keyword: 
silicon-germanium,  bipolar transistor,  tunneling,  

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Summary: 
The low bias region of the base current has been studied in SiGe HBTs and shown to arise from tunneling at the emitter periphery. Tunneling also describes the reverse bias base-emitter current, which we believe is enhanced by mid-gap states. The reverse bias causes damage to the base-emitter region, increasing the base current. We also show that after a short period of severe reverse bias stress the base current displays random telegraph signals. These phenomena are often observed in silicon bipolar transistors, confirming that the incorporation of SiGe has not produced any other undesirable characteristics.