Characterisation of NPN and PNP SiGe heterojunction bipolar transistors formed by Ge⁺ implantation

Mitchell, M., Nigrin, S., Cristiano, F., Ashburn, P. and Hemment, Peter L. F. (1999) Characterisation of NPN and PNP SiGe heterojunction bipolar transistors formed by Ge⁺ implantation 1999 Symposium on High Performance Electron Devices for Microwave and Optoelectronic Applications. pp. 254-259.

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Abstract

This work compares NPN and PNP SiGe HBTs fabricated simultaneously using Ge⁺ implantation in the base to achieve an average Ge concentration of 4 at.%. Electrical measurements are presented and discussed with TEM and SIMS analysis. The results show that the PNP HBTs give superior performance to the NPNs, as they have more ideal collector characteristics. The NPN HBTs exhibit collector-emitter leakage. Both types of Ge⁺ implanted device have non-ideal base currents. TEM images show that both NPN and PNP devices have a high density of defects in the Ge⁺ implanted area. The electrical results are explained by the opposing effect of the Ge⁺ implant on the diffusion coefficients of boron and arsenic, as seen in the SIMS profiles. The increased emitter diffusion in the NPN HBTs creates a narrower base region, which is more prone to collector-emitter leakage. The hairpin dislocations in the base are thought to be the cause of the base current ideality deterioration.

Item Type:	Article
Additional Information:	Mitchell, M.; Nigrin, S.; Cristiano, F.; Ashburn, P.; Hemment, P. Characterisation of NPN and PNP SiGe heterojunction bipolar transistors formed by Ge+ implantation. 1999 Symposium on High Performance Electron Devices for Microwave and Optoelectronic Applications, 254-259. © 1999 IEEE. Personal use of this material is permitted. However, permission to reprint/republish this material for advertising or promotional purposes or for creating new collective works for resale or redistribution to servers or lists, or to reuse any copyrighted component of this work in other works must be obtained from the IEEE.
Divisions:	Faculty of Engineering and Physical Sciences > Electronic Engineering > Advanced Technology Institute > Ion Beam Centre
Depositing User:	Mr Adam Field
Date Deposited:	27 May 2010 14:39
Last Modified:	23 Sep 2013 18:32
URI:	http://epubs.surrey.ac.uk/id/eprint/1254

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