The radiation tolerance of strained SVSiGe n-MODFETs is investigated, using 10 keV X-rays, 63 MeV high energy protons, and 4 MeV low energy protons. The effects of radiation exposure on two major device design parameters (L SD and L G) in T-gate Si/SiGe n-MODFETs devices are examined. A strong dependence on source-drain spacing is observed for both the DC and RF characteristics. A drift-diffusion TCAD framework is used for 2-D device simulations. We believe that the low energy protons damage the SiGe/strained-Si/SiGe lattice, leading to partial strain relaxation. The conduction band-offset (CBO) of the strained SiGe/Si heterqjunction is lowered leading to higher gate current leakage. The presence of radiation-induced bulk traps in the unrelaxed SiGe layers on the device behavior is also investigated.
Bibliographical noteFunding Information:
Manuscript received July 21, 2007; revised August 30, 2007. This work was supported by the Defense Threat Reduction Agency under the Radiation Hardened Microelectronics Program, an AFOSR MURI program, NASA-GSFC under the NASA Electronic Parts and Packaging (NEPP) Program, NAVSEA Crane, ATK-Mission Research, IBM, and the Georgia Electronic Design Center at Georgia Tech. A. Madan, B. Jun, R. M. Diestelhorst, A. Appaswamy, and J. D. Cressler are with the School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA 30308 USA (e-mail: firstname.lastname@example.org). R. D. Schrimpf and D. M. Fleetwood are with Vanderbilt University, Nashville, TN 37235 USA. P. W. Marshall is a consultant to NASA-GSFC, Brookneal, VA 24528 USA. T. Isaacs-Smith, and J. R. Williams are with Auburn University, Auburn, AL 36849USA. S. J. Koester is with IBM T. J. Watson Research Center, Yorktown Heights, NY 10598 USA. Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TNS.2007.907871
- Bulk traps
- Displacement damage
- Radiation effects